Exactly, and fields are different everywhere.
A 75 deep, Cat4/5 with a peloton averaging 27-28mph in Colorado, with 6-8 rider teams riding as teams, is a lot different than a 10 man field averaging 24mph in Southern New Jersey. Plenty of Cat4/5 Youtube personalities who have raced in smaller / slower fields giving advice like they’re a Cat1/Pro.
There is a lot to learn for yourself and the difference between knowing what to do and doing it comes by practice. As I mentioned above, I know not to be on the upwind side in a crosswind, everyone knows that, but I made a split second choice and watched it blow up in my face real time, as it’s happening. It happens and with experience, you make less of the wrong choices, but that only comes by doing it.
To the OP, just do you, at your pace, and introduce yourself to people at the races. If you get dropped, don’t worry about it and finish with a hard effort. You paid for it, your schedule should fit around your race being a hard effort, so finish it up by making it a hard workout and aim to do better next time.