Sharepoint formatting issues

Hello

I have different questions with formatting a list.

1. Is it possible to Format a column width as Auto or fixed size. Heard that although this is described in https://docs.microsoft.com/en-us/sharepoint/dev/declarative-customization/column-formatting it is not possible.

2. Can I rotate the Heading of the column to 90 degrees.

3. Is it possible to colour the heading of a list.

Thank you for your help tried many ways