The TOC 1 style controls the formatting of level 1 entries in the table of contents, TOC 2 controls the formatting of level 2 entries, etc.

Your TOC field, or more specifically the \o "1-2" switch, tells me that styles whose "Outline level" (as seen in the Paragraph dialog box) is 1 or 2 are included in the TOC. Heading 1 paragraphs always have Outline level 1, and Heading 2 paragraphs always have "Outline level" 2; this is hardcoded and can't be changed. In this case, you should modify the TOC 2 style, which corresponds to Heading 2. Is that what you have been doing?

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional