How to paint small bathroom multiple neutral colors?

You can do stripes, but that is a very meticulous painting project whether you go vertical or horizontal.

You could do something like wainscoting with 2 different colors.

Paint the walls one color, then a different color for trim & doors, another for vanity & cabinets.

Do you have a picture? Regardless how you decide to paint your bathroom, be sure to use a mildew resistant primer such as this one. https://amzn.to/2DeGUk5

You could do an ombre look. Here are some ideas on =ombre%7Ctyped&term_meta[]=paint%7Ctyped]Pinterest.

You could do 1 wall a darker neutral color and the other walls a lighter shade of that color to give some contrast, but still keep it all neutral.

I used soft neutrals in this accent wall. https://www.alifeunfolding.com/blog-1/2018/8/3/adding-coastal-vibes-to-master-bedroom?rq=%20walls