second hardest match-up in the meta-game IMO behind our Marth Match-up. The real problem is that we can't do much against him. I'll let someone much more proficient than I tell you better how to KILL Fox, because Killing is always a hard thing for Peach. But I can tell you how not to die so much.
First off, Turnips are the key. Throw Turnips as you approach. Either Fox gets hit and your approach is successful, he dodges and your approach is successful, he shields and your approach is successful, he attacks and your approach could be successful, he catches it and your approach is done for, or you miss and you try again. Don't feel like you need to be the aggro character. That's Fox's job. The whole point of Peach is to be defensive. Use his mistakes against him. Float the Up-throw up air or be ballsy and try and dodge to N-air it. Remember Up-air is useful, and B-air combos are a thing. Toad is situational, but could also help.
Another tip, watch Armada. When you're done, watch some more Armada. Then watch Wife, go back to Armada, watch DoH, and MacD and WATCH ARMADA. My god that man handles Peach like he's IN the game.