But how do you perform such trades?
By directly sending money to each other. If you are trading without an escrow, then one person sends fiat to the other via something like a bank transfer, PayPal, cash, etc., and the other person sends bitcoin back. If using an escrow, then the bitcoin seller deposits the bitcoin to the escrow, the buyer transfers the fiat, and then the seller releases coins from the escrow.
Some platforms like Bisq go one step further with the escrow, requiring both parties to make a security deposit of bitcoin, and making the escrow trustless by using a 2-of-2 multisig between buyer and seller.
Localbitcoin is one of the most preferred p2p platform who is exist in the market for very long time.
LocalBitcoins used to be a good platform, but now requires just as much KYC as any other centralized exchange, and also requires you to give up custody of your coins by sending them to their wallets. There are endless reports of customers being locked out of their accounts and unable to access their coins. They are completely centralized, and best avoided.