That is left for you to do your research, there are a lot of mixers you can choose from, and you can check their websites to know how they work before using them. But as i said in my previous post, you are going to lose custody of your coins when you use mixers, and if you want a self custodial privacy solution, use CoinJoin implementations. Recommending a particular mixer to people would be difficult right now, and that is because we do not know which mixer would fail or be seized next, and you don't want people to lose their money because you linked them to a particular mixer.