Is being unbanned a thing? what would be the qualifications.

I've heard in a few cases RIOT has unbanned certain players because they are in a better mindset and have learned their lesson. Well I've been around for 3 seasons since my first account was banned. Yes i was extremely toxic, (said terrible things, was more focused on everyone else's play than my own etc.) But in the last couple years i'd like to think I've changed for the better. Everyone has a bad game once in a while, personalities clash sometimes. I guess i just wanted to know if there is any way to get my old account back. Any feedback would be appreciated.