One way to grow your coin supply and earn more BNBs is to stake your coins on Binance. This is when you lock in your tokens to a particular project for a specific period of time. You can find different staking products in the Binance Earn section of your account with different rewards and lock-in time frames.
Alternatively, there are several crypto wallets that pay interest when you lock your Binance coins into their savings account, and this applies to other crypto assets too. It’s always worth shopping around for wallets if you want to get more serious about crypto.