Select a case that matches your purpose
Uppercase can suit a short label, while lowercase can normalise a rough list. Title case capitalises the beginning of each whitespace-separated word; it is not a newspaper or academic style-guide engine. Sentence case lowercases the text and capitalises recognised sentence starts, so an existing acronym can change.
Example: turn rough text into a readable heading
Converting 'a better way to work' to title case produces 'A Better Way To Work'. Your chosen editorial style might prefer a lowercase 'to', which needs manual adjustment. Check brand spellings such as iPhone and any initials before publishing, rather than accepting a mechanical case rule as a final proofread.
Keep capitalisation separate from writing quality
Case conversion does not correct factual mistakes, word choice or grammar. It can also change emphasis that matters in product names, identifiers or passwords. Work on a copy when exact capitalisation carries meaning, and preserve the original if you may need to restore proper nouns or technical abbreviations.