Are you ready to do KYC? Because the easiest option to buy Bitcoin is from a centralized exchange such as Binance/coinbase, where you need to do KYC to buy/sell/withdraw cryptocurrencies.

If not then you can use Bisq like platform which is no-KYC p2p and let you to connect with the people where you can buy bitcoin with fiat too.

Unpopular method, buy directly from other forum user and you can find some in Currency exchange