Most websites that allow you to "stake" BTC would first need you to convert it into a Wrapped token which is basically ERC-20 version of bitcoin governed by a set of actors that decided to be custodians of this transfer. Once you have this renBTC or wBTC, you can then use platforms like AAVE, COMP etc to provide it to their lending pool. The returns would really not be a lot though. Most of these sites had rewards for early users when the liquidity was low.

Nowadays there is enough liquidity and to have a good return, you will have to go into riskier assets and explore newer platforms. There are a ton of them and it is hard to discern between scams and good ones. Better to keep part of that BTC safe as a SoV. The rest can be used for the risky plays after you do your own research. For starters, I can recommend you to check a product known as "Barnbridge Smart Alpha".