Welcome to the forum!
It is still early to tell what the restrictions, if any, will be come September. We have to see how the summer goes.
Also the EU is supposed to activate the Green Pass in a matter of days (which is give under 3 conditions: either you're fully vaccinated or have a negative covid test in the 48 hours before travel or fully recovered from having had covid in the last 6 months), you will not have to do any quarantine and can move around throughout the EU/Schengen countries.
At the moment, masks are still required outdoors as well as social distancing. But that is likely to change over the next few weeks. I am catching up on all the news and will be making updates on the website/blog over the next week and keep updating the info so that you can more easily find current details.
Look forward to seeing more travelers from afar returning to Florence and Tuscany this summer! It has been quite a shock to see the centro storico so empty for so long.