A lot of tfvars best practice

If we have quite a lot of terraform environments, there will be a large number of tfvars files, what is the best strategy and configuration in this case?
We have at least 10 environments, and we do not believe that a small number of environments such as prod, dev, staging, etc. will get through.
Currently, we are splitting only tfvars into separate repositories to increase loose coupling, but I don’t think this is a good idea.
If there is a good branching strategy, I would like to know about it.