For example, in Russia any exchanges is semi-illegal. Such business exist but it can't work publicly. And commission can be from 2% to 10% depend on the market situation. What is your situation?
Near me, there are Bitcoin ATMs with cash out options. (I am in the USA).
They only require one form of government identification (like drivers id) and let you cash out at the ATM. You only provide verification once, after that it is just facial recognition. They take a 15% fee on sales under 500 USD, 10% from 501-2000 USD, and a 8% on anything larger..
It seems to be completely legal, they used to only allow buying. When the ATM version of crypto "cash out" was introduced really spurred growth in our town. A lot more people in to crypto once they realized they can get their money out instantly from an atm instead of waiting however long it took for bank transfer or having to deal with p2p marketplaces online.