This is what I have switched too
https://theboxingmanagergame.com/
There is no PC release unfortunately. But it is light years beyond where TBCB ever was in terms of actually managing fighters.
You can sign boxers as teenagers, have them be amateurs in various local, national and regional tournaments and eventually the Olympics if they are good enough (there are Olympic trials as well)
Then at a certain age if they good enough, they will ask to turn pro and you can either let them or try and keep them amatuer a bit longer if you think the need more development.
But there is a chance they will leave your gym.
Then the professional level has so many belts and titles, again with local and national and regional belts and then world titles.
Every modern weight class is included or you can have the traditional ones.
Boxers move realistically between weights. Usually at the lower weights and moving up as they get older.
Moving down is a bit harder and they cannot go as far down as cutting weight gets harder.
The fight engine has gotten a lot of improvements and is pretty top quality now.
The game gets regular updates.
They have said a desktop version is possible, but I have not seen any movement on it in a long while.