[Enhancement] Auto expand Textarea field's height (box size) based on the content

[mmarj]

Description: Currently, if you use the "post content" or "textarea" field and write a long thread, you will see it won't expand the inside box (height) of the field based on the screen view. Hence, you won't see all the texts at a glance. You need to scroll up to see your off-screen texts. Video- https://screencast-o-matic.com/watch/c3noDqVbllj.

Expected behavior: Can we have improved this behavior of the TinyMCE editor like this or as like our registration form's notification email editor?