Do you want to buy Bitcoin or trade ? If you want to buy from the safest exchange then you should choose Bisq Network which is fully Decentralized P2P exchange. Here is the link: https://bisq.network . Just download their official app and proceed.

Anyway to trade Bitcoin there are many popular centralized exchanges which have much more features than a DEX which no one can decline. You can try MEXC, Huobi Global and many more. Just don't leave your funds in the centralized Exchanges. Move your funds to a non custodial wallet while holding period and after trade move again to your wallet.