As Charles wrote, creating a building block is very helpful if you want a format which doesn't already exist in Word.

Of course, even with a custom format, you still have to update the TOC manually after you have changed something in the document. Just click in the TOC and press F9. If you are prompted to update the whole table, choose to do so.

In addition, a building block won't change the appearance of TOC entries. For those to change, modify the built-in TOC styles which control the text in the TOC (TOC 1 controls level 1 entries, TOC 2 controls level 2 entries, etc.).

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional