I have been changing book titles listed in all capitals to title case, however as there doesn’t seem to be any guidance on this subject, a user could rightly dispute my edit.
I prefer title case which broadly means the first letter of each word is capitalised except for short prepositions, articles, and short coordinating conjunctions. For example: Little House on the Prairie, A House for Mr. Biswas, etc.
It might sound confusing but there are online conversion tools available (just be aware they are not always accurate). One of my favourites is https://capitalizemytitle.com/
These rules do not apply to other languages which might have their own set of conventions.