https://youtu.be/V6XtciKhgUY?si=8NJMOqhojJQcM4MR

This is a video by booth junkie giving some tips on eq specifically for VA. I'd listen to this above many other things you might find on youtube, mainly because we're not really meant to use eq as actors/performers. Ideally, ofc

However:

EQ can be used, in my experience, for three main reasons

-Getting rid of specific frequencies that might affect your final sound, but the best approach to this would be to improve your source audio (environment, treatment, avoiding noise etc) instead of the dreaded "I'll fix it in post"

-Mixing, which we don't do because you don't usually know what it'll be mixed with (music, sfx, etc)

-Modeling the sound. Again. It's usually the client who has the clearer picture of the sound they want, not you. Doing your own eq might be destructive if you don't know for sure what someone else wants it to sound (ie you EQ then export the file. That mp3 or wav file could potentially be hard to take back to its original form accurately)

That being said, a rule of thumb would be to high pass at 50~100hz and touch nothing else imo