Selectively clean manual formatting (tabs but not font styles)

So I’ve got a roughly 90,000 word document that, sadly, uses ruler tabs to indent paragraphs. This has become a problem, and I need to remove them and replace them with paragraph-style indents, but the only solution I’ve found that works is clearing all manual formatting using Ctrl+M.

This is a frightening prospect, because the document also contains a lot of important italics that would be wiped out by just selecting the whole document and clearing manual formatting.

I’m unable to search-remove these tabs by searching for \t, ^\t, or \n\t with regular expressions as suggested elsewhere. The Format>Paragraph>Tabs>Delete all option also does nothing for me.

Is there a way to selectively remove all these ruler tabs without removing other manual formatting such as italics?

I’m not opposed to breaking open the ODT in rawtext and editing whatever the file format underneath is, if that’s what needs to be done. The thought of combing through a before and an after version of the document re-inserting italics everywhere is giving me nightmares already.

I suppose that the only option for you would be to create (adjust) proper character styles for your italics, then search for italics (find all) in text and applying the character style to the result; and then clearing direct formatting, which would not clear applied character style.