There's a bug in iOS and macOS that causes a crash if you paste into an empty multi-line field. You can work around it by typing something (just one letter) into the empty field, then deleting it, then pasting.
When I tried it, with Settings > General Settings > Paste Text Formatting turned on, the bold/italic/underline and markers were copied. Unfortunately, text colors are not copied. I'm not sure why; when I try pasting into other apps, the colors copy over in some apps but not others.