I would not start a new one, keep the one you have as it has a 20-year vets cape and not many can say that. The game is so much faster to level up now from the days of classic.
Do not delete your friends list even if its random letters/numbers and you don't remember who each is as 1 day they may come back and be active again and if they do the name will change but it will be the same person, just like your old account might be on someone else's friends list but showing random letters till you changed it.....if that makes sense.
If you like group content, then it might be better to find a clan with older players that like doing the same as you and do not join the first clan that comes along as some just want people to join to keep the numbers up for the sake of it.
Your account will give you access to both RS3 and OSRS games but if you play on OSRS you will start with nothing so it's like a new account already.
13-Nov-2023 16:40:13