If your goal is cat A, just do a 20 min TT effort and keep trying to beat your own time record.
I was in Cat A (and am now back again).
2 weeks ago i did 4.5 w/kg for 20 min TT and won it in the 690+ category.
But it appears that they tinkered with the metrics and you need to do a <5.2 w/kg 5 min effort every 3 months to not get demoted to B.
You can get there either by >= 5.1W/kg zMAP or >= 4.2W/kg zFTP. A 20 min PR would affect zFTP but not zMAP. It varies but for a lot of people (most?) zFTP is more than 20 min power.
My zFTP is currently 33 watts lower than my 20 min power (317 v 350)
Zwift has my FTP at 332, and training peaks at 328.
90 day power has always been used