No ... that version is only for the
DJI FPV drone, DJI Air units &
DJI FPV googles.
It's not possible to do a backup of a drone firmware ... if something goes wrong you can always chose to flash over another version instead though... as long as DJI doesn't decide to include a anti-rollback.
Go here & download the correct DJI Assistant 2 version for the
Mini 2 -->
DJI Mini 2 - Downloads - DJI
Under the "Firmware Update" section you can chose what ever version you want ... from the release notes it doesn't seem as DJI have put in any anti-rollback function yet (release notes here -->
https://dl.djicdn.com/downloads/DJI_Mini_2/20210616/DJI_Mini_2_Release_Notes_EN.pdf )
And ...
Just to have it said (as many mix up drone firmware with app version) ... IF you mean change the app version instead of firmware, then yeah, you can downgrade if you can find the older installation file somewhere on WWW. Backups, yeah sort of possible but only if you have a rooted Android or a Jail breaked iOS. There is numerous of phone apps that will backup both apps & appdata so you can go back with both the app & all the settings.