Go with Qt6, you can always switch to Qt5, if issues occur. Focus on the Anki basics (read the manual: https://docs.ankiweb.net/), establish a workflow and install add-ons when needed for particular purposes. No one can tell you, what you will need. It is perfectly fine to run Anki without or just a few add-ons.
Thanks for the response. However, that opens up a corollary question. If there is an add-on that I want to use but it doesn’t work with Qt6 v2.1.61, do I just start downloading older versions till I find one that the add-on works with?
I would not use an old Anki version to install an add-on that is incompatible with newer Anki versions for the first time. After all, the new versions have also brought bug fixes and new features. Sometimes add-ons are abandoned and it is time for the user to find another solution (forks, similar add-ons, other workflow).