the truth is... there's no right answer! you don't necessarily have to clean up after sex, it all comes down to personal preference and the type of sex you are engaging in.
the vagina is a self-cleaning body part and will, for the most part, take care of everything that needs to be 'cleaned' after sex. many doctors recommend peeing immediately after sex to flush out any bacteria that may have entered the urethra during sex, which can help prevent UTIs.
outside of that — any clean up is more about personal preference. for example, if you participated in intercourse in which your partner ejaculated inside of your vagina, it will leak back out over the next several hours (sometimes into the next day). if you find that uncomfortable, you can use a dripstick to soak up the semen in the vaginal canal immediately after sex. you can also hop in the shower after sex for a quick rinse, or use a towel to wipe away excess fluids.
anal sex is a little bit different. the skin inside the anus is thin and delicate, and having anal sex can cause microscopic tears and bleeding. if bacteria from your anus (including poop!) gets into those tears, it can cause an infection. because of this, it is best to shower after anal sex and rinse away any lingering bacteria.