Copy contents with indentation

I am trying to copy out a table of contents from a document complete with indentation.

However, this is remarkably different as the indents appear to simply be using the ruler (SHIFT+CTRL+R) i.e. not real indents.

How would i resolve this?

Reformat the pasted content in the another .odt document by Paragraph styles.
If you used the default TOC paragraph styles, then it requires a few click only. (Those styles exist in an another .odt file too.)

To be clear you are saying

Copy and paste into a new file
Set formatting to default paragraph styles (This left aligns and normalises the text sizes)
Reformat (manually add back in via TABS?)

In other words no automatic fix?

If I copy the TOC from one of my .odt documents into a new document the indents remain. If I needed to change the indents then modifying the paragraph styles; Contents 1, Contents 2, Contents 3 would still work in the new document.

This is roughly equivalent to paste as unformatted text.

Which means you direct format everything instead of using styles. If you’re looking for an “automatic fix”, learn styles.

Applying an existig Paragraph style will set all of the desired properties.
It is a half-automatisc solution.
(if you not used direct/manual formatting properties fot the TOC in the source file.)