No, there will be 2 different categories of FSM.
Targeted FSM - income less than £7400, get FSM and attract equivalent of pupil premium funding. It's a school decision on how the PP funding is spent. Much the same as current PP.
Extended FSM - receives Universal Credit but income is above £7400, get FSM but no other assistance
Not eligible - does not get Universal credit
With extended FSM, more families will be eligible. However currently no-one has been rechecked for eligibility since 2018, if you have been eligible, at any point, even if just for a month, since 2018, you remain eligible even if your circumstances change. Until Sept 26. There will almost certainly be some families who are currently receiving both FSM and PP and have got used to that level of assistance who's circumstances have changed so that they no longer receive UC, who will lose their FSM and PP.
Families will also be rechecked annually so just because you get FSM in 26/27 does not automatically mean you will still get it in 27/28.