Can I wear my Apple Watch series 6 in the shower

Yes

Showering with Apple Watch Series 2 and newer is ok, but we recommend

not exposing Apple Watch to soaps, shampoos, conditioners, lotions, and

perfumes as they can negatively affect water seals and acoustic

membranes. Apple Watch should be cleaned with fresh water and dried with

a lint free-cloth if it comes in contact with anything other than fresh

water.

See Can I go swimming or take a shower with my Apple Watch?