The bitcoin mixers such as Bitcoinmixer.io and Coinmixer.se are good bitcoin mixers with good reviews.
I don't do bitcoin myself but I've read good things about those two bitcoin mixers and they are pretty widely known by people who need and use bitcoin mixers.
Just be aware that using bitcoin mixers can be illegal depending on your state and it could be seen as money laundering.
Especially if you use the bitcoin mixer on large amounts of bitcoins.
But for the most part you should be able to get away with using the bitcoin mixer.
Also I've heard that the FBI was using bitcoin mixers for catching money launders or something similar.
Mixing bitcoins helps protect privacy and can also be used for money laundering by mixing illegally obtained funds. Mixing large amounts of money may be illegal, being in violation of anti-structuring laws.
The existence of bitcoin tumblers has made the anonymous use of darknet markets easier and the job of law enforcement harder.