Time jumps are usually a reliable way to spice up a show that's getting stagnant, and it definitely worked for Riverdale. The main characters got to leave the crime-ridden town (at least some of them), and develop personalities independent of high school and their lives with each other.
While some characters like Jughead couldn't cope well with adult life and ended up becoming a worse version of himself, just like Cheryl and her continued stubbornness, others thrived in the time that they had away from home. They excelled in their careers, helped their communities, and still managed to preserve their generosity and determination.
Fangs Fogarty
One reason why the time jump was a good idea was that characters could explore things beyond high school, and explore their relationships better. So, while Fangs went to the University of Pittsburgh, he decided to stay with Kevin, which continued when they returned to Riverdale.
Fans were able to see a new side to Fangs that went beyond the Southside Serpents and revenge — he had evolved into somebody who was ready for a long term relationship, ready to settle down with Kevin, and mature enough to have a baby with him with Toni as a surrogate mother. He also tried polyamory to keep his relationship alive, which was refreshing to watch. He graduated from being just a side character to someone with a rich inner life, who also was capable of helping Archie and the town when required.
Toni Topaz
All of Riverdale's teens could range from heroic to villainous, but Toni really showed her dedication to the town and the school after the time jump. She always had a lot of empathy and the will to help in her, but only the age of time really brought it to light for everyone to see.
She educated herself in social work and came back to Riverdale to assist and the community, whether it was vulnerable teens or working mothers. Her contribution as a counselor was huge, and it was nice to see her do something beyond just coddling Cheryl and doing her bidding. She had matured beyond Cheryl's games, and her goals in life were very different from what they were when she was in school.
Archie Andrews
Archie Andrews was a protector, and the things he said on Riverdale summed up his personality well. Thankfully, he didn't lose his courage and bravery through seven years, and he came back even more valiant and ready to commit to bettering Riverdale. He had gone through a lot in the army, but that didn't make him jaded or cynical.
He was still the first person to rally the troops to fight Hiram and his dirty tricks, he made a fire department and a football team from scratch, fought off Ghoulies, and even proved his dirty commander wrong in front of the authorities to bring justice to his fallen compatriots. He also had a newfound sense of self-respect around Veronica, which was a big change from school life. Archie also realized that Betty was better for him, which showed true growth.
Kevin Keller
Many would think that Kevin had returned to his old tricks of cruising the Fox Forest, which meant that his character was still the same, but the difference here was that he had a breakthrough. It finally dawned on him why he did what he did, and took a very difficult decision to end his engagement to Fangs and do away with all the baby plans.
It takes a lot of courage to end things when they've gathered momentum, but Kevin did it for himself and for the good of his potential family. Fans also loved that he had majored in drama, and come back to teach the art at Riverdale High, which meant that he was really accepting his identity and following his dreams.
Reggie Mantle
Reggie may have been a total jock in school, but that didn't mean he had an easy life. With an abusive father, and being envious of Archie's life, Reggie didn't have it easy. So, he decided to earn a quick buck by becoming Hiram's lackey, and he was a great foil for the other righteous characters on the show.
However, after feuding with his friends and repaying the debt that his father owed to Hiram, he really evolves into a man of his own. Reggie had battled his abusive father and the trauma he had caused him, worked for Hiram to make a point, and then mended things with Marty Mantle. His arc after the time jump may not have made sense at first, but it wrapped up nicely eventually.
Hermione Lodge
Hiram's long-time love and ex-wife may have had limited time on the series after seven years of ing, but her storyline seemed to be one of the most positive ones. After years of being used and manipulated by Hiram, and getting her hands dirty in his mafia business, she finally found herself, far away from him.
She became a successful Housewife on a reality show, made money and gained recognition for herself, and saved herself from small town scheming. She also shared a great relationship with Veronica, which was sweet to see since they had been through so much earlier. She also cautioned her about Chad's competitiveness and generally found her peace away from her husband.
Josie McCoy
After Josie's brief stint in the series, she left for New York to make it on her own. Her return to Riverdale was an empowering one — she faced her friends who had put her down and tried to make her feel small when she was a teen, but also fixed things with them and refreshed their ties with them.
Most importantly, she reached out to Valerie and Melody to apologize for her behavior and for leaving them behind. She decided to take them on tour with her, permanently. That made them a part of her band and gave them a share of the success they rightfully deserved.
Betty Cooper
Amongst the teens who went out and chased their dreams, Betty was the first one. Her affinity for crime and mystery was an old one, so it was natural for her to the FBI and get trained. In her training period itself, she slipped up and got caught up with the Trash Bag Killer, but it only demonstrated her determination is getting justice.
After the harrowing tragedy of Polly's murder, she again solved the mystery of the Mothmen killers, retrieved her body, and even got her mother to grieve and accept that only the two of them remained, with the twins.