You can use Binance to buy/ Sell cryptocurrency. Make an account on Binance and do a KYC to activate your account. There is a section called P2P, where you can sell/ buy USDT or Bitcoin in your local currency. After purchasing BTC or any other coin, do not store it on Binance Exchange, transfer those tokens ASAP to Metamask or Trust Wallet (You can use other wallets as well).