It’s really hard to say because as you alluded to in your question, race craft plays such a huge role. Like you can probably hang on, animate races and feature in the crux with less than 3 w/kg FTP if you play your cards right, or you can get dropped with 4+ w/kg FTP if you don’t and are like braking hard into every turn and stuff like that. Plus it depends who shows up. In the novice and 4/5 crits you could get really strong dudes that happen to be 4/5s right now but will likely be passing through these categories pretty quickly.
My advce would be, come in with what i would call, i dunno, a “balanced mindset”. Like you accept that you can have a sh*t race or get dropped and it’s no big deal, but also that you have every right to be there and that you can hang with anyone who toes that line alongside you, even if they have more power than you or are fitter right now, because every phenotype is different and there are so many ways to be successful.
When the race starts go hard in the beginning. You do not have to lead (and probably shouldn’t lead), but don’t be afraid to burn matches to keep yourself in the first third of the field, towards the pointy end. It’s correct to follow wheels and draft but you don’t want to get so obsessed with saving energy that you let yourself get too far back and start getting gapped when people in front of you fall off the pace, or because of the accordion effect that tends to happen in novice races when everyone brakes before corners and then sprints. If you burn a few matches to stay in front of that, you can save many more matches by avoiding getting caught in it.
Then, even if you are on the limit and you don’t think you can hang, keep going, keep trying, try as hard as you can to close every gap. Because chances are, everyone else might be hurting just as bad as you, and if you can survive the first half and avoid getting dropped, you get to that magical moment where field has winnowed (because bunch of dudes got dropped) and the pace seems to slow. It may not actually slow, it could just be that it’s easier to maintain speed with less effort because fewer riders diving around and braking, but regardless, it feels suddenly like it’s effortless and everything clicks. THAT’s when the real racing begins; you can follow wheels carefully and start making moves. It’s super fun.
Then, get creative, enjoy yourself and race your race in your own particular idiom. Some people like to be conservative, i prefer to attack because i hate finishing a race and thinking i still had more to give. I don’t love blowing up in a stupid move, but i hate it less than feeling like I missed a chance to play my cards, if that makes any sense. 
