You are right this feature is still not unavailable, as to why something this basic is missing I don't get it, the same can be done for record detail pages though
Do upvote the idea
The rich text area only supports some of the formattings and not all that is possible using style.
Unsupported styles are removed and added just as plain text.
Refer to this salesforce article for more details.
NOTE We recommend using the toolbar to format your content. The rich
text editor provides only a WYSIWYG interface. You can’t edit HTML
tags. When ...