How can you forward delete all in macOS?
Within default macOS apps (e.g. TextEdit) as well as other Apple apps (e.g. Pages) you can use the controlK keyboard shortcut to delete the text between the cursor and the end of the line (or paragraph). However, this isn't supported by default in many 3rd party apps (e.g. MS Word).

However, you can use the optionfndelete keyboard shortcut (in standard keyboards) to delete everything to the right of the cursor up to the next space. This works in many 3rd party apps.

If you have an extended keyboard, then you don't need to use the fn as you have a dedicated forward delete key.