At CDG you will disembark the plane from Florence on the tarmac and a bus will take you to actual terminal 2F. The flight from FLR is operated by Air France.
The flight from CDG to the US will likely depart from terminal 2E, which consists of the following sub-terminals, or Halls:
2E Hall K, 2E Hall L, 2E Hall M
Your flight could depart from gates in any of the above Halls.
See diagram below to get an idea of the CDG layout
https://share.google/f7hDVMpMvmV28mfv6
To go from 2F to 2E Hall K you walk across in the underpass. Then Hall M and Hall L are connected to Hall K via LISA people mover (also underground). Hall L can also be walk to from 2F.
There are also buses, airside, that connect the 3. So when you disembark check your departure gate on the display or ask the AF people. If for example the gate is K30, then it departs from Hall K. Then go to that Hall.
90 min is sufficient, assuming no arrival delays. There will be long walks and also passport control to go through on your way to your US bound flight. I don’t think there is security check anymore.
You can refer to the link above and you can also find plenty of YouTube videos online that walk you through the transfer process, just Google “CDG from 2F to 2E”(then check the sub-terminals K, L, M). It’s a huge airport so depending on which Hall and depending on the line at passport control (they will check your passport on your way out of France) it could take from 30 min to 50 min for the transfer. Typically from the time my plane from Florence lands to the time I am at the gate I need at 2E, it takes me 45 min to one full hour.
So use the bathroom just before landing and try get there to your gate first, then you can relax once you are there, there is plenty of food and wine available at 2E. I know transferring at CDG is unnerving, but 90 min should be ok. I’ve made it in much less time due to flight delays. Once my out Florence plane was late, and while still on the tarmac some AirFrance personnel came on board, before anybody could exit, yelling to all passengers going to San Francisco to go with them, they put us on a little van and zipped through the airplanes on the tarmac at full speed, it was like a movie, then they dropped us at our departure terminal through a special door, and we were immediately through passport control at 2E just where we needed to board. AF really makes sure they don’t have to pay for your hotel if you miss the flight. Only once we didn’t make our flight to SFO, as it was snowing in Paris and the flight was canceled. They put as in an airport hotel at Roissy, near the airport, we then took the RER downtown and we had dinner at the Latin Quarter. It was cold as hell, but Paris is well worth a Mass, as Henry IV famously said.