You want something that manages different versions of Python itself. pyenv is a popular option for doing this, but I'm partial to rtx which is largely language agnostic and also handles Python virtual environments in a very elegant way.
I used asdf for a long time and recently switched over to rtx (https://github.com/jdxcode/rtx) and so far it's been a better experience for me. I must have screwed up something years ago in my dotfiles, but when I setup asdf two or so years ago, I kept running into odd issues - the wrong version of ruby being used for running rubocop/rspec, vim being unable to autofix styling, misc other tools not working as expected when maintaining several versions of them. I installed rtx as kind of a hail Mary and it's been much more smooth so far.
pyenv is really slow. It'll increase the time it takes to run `python` by a ton. For me it makes `python -V` take ~120ms but without pyenv it only takes ~13ms.
I wrote an alternative that has 0 overhead called rtx. https://github.com/jdxcode/rtx