Reminded that I have been meaning to raise this by this post by @andyG. I write everything in Markdown (and would actually normally be reluctant to use a tool that didn’t facilitate its use). A Markdown multiline text field, I feel, is very useful. It would also be handy in email automation and PDF creation as it would make formatting these easier for most people. As a quick example:
# Heading One some text ## Heading Two - List one - List two **Bold** *Italic*
For more detail, you can visit Markdown Guide.