So the <svg.*?>.*?</svg> should work to grab tags that are svg. But emoji are considered actual text, so it won't capture them.
Instead, use \p{emoji} to match emoji characters, although it may have some difficulty with flags.
Match flags with \p{emoji}{2}. Still some limitations here, because two emoji next to each other would also match.
However, if you are just removing them, simply find \p{emoji} and replace with "" (nothing) and it should work in most cases.
I'd suggest getting rid of the emoji first, then going after the <svg> tags.