Don’t know if you’ve heard of these but, playing earbuds. They are for playing in a band while protecting your hearing. They’re great, muffle everything but you can still hear people talking and loader noises (both muffled)

Noise canceling headphones(you can still hear through them but it makes things less ouch), or noise canceling earbuds. also it is nice to have stuff to fidget with!

Look for a couple of places you can go to that’s away from most of the people so that you know where you could go if need be

Along with everyone saying to get earbuds or noise cancelling headphones, remember to pack a bag with you!! In this bag, put some fidget toys, some comforting textures/smells/foods, and a bottle of water/your favorite drink. This will help regulate you through your festival experience to orevent overstimulation. Also remember to check for exits/a place to go where it's quiter/less intense for you. Bring sunglasses if you're light sensitive. Have someone on speed dial in case you need to hear their voice to calm down, or go to this app, y'know, we all understand the struggles!