You could do it with the REST api if you are programatically inclined. Or if this is a one off kind of thing you ould try an add-on from the marketplace that could do it. I've provided a link below (I've no affiliation with them).
Hi Community! I’m Elaine, Confluence Product Manager. You may have read my earlier post about page tree in space navigation sidebar. I'm excited to share another improvement that helps you organize ...
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