What you styled is what gets posted
Social platforms have no rich text of their own. Native now converts your formatting into characters they do accept, so the caption lands looking the way you wrote it.
What's new
Bold and italic in a caption are rendered before the post is handed to the platform
Styled numbers are re-imported as marked-up text, not as glyphs you cannot edit
Rewriting a caption counts as a real change again, so nothing is quietly skipped
The formatting holds across every channel a post goes out on