You can create a style whose font is set to "+Body" which means that it uses whatever font is the default for the current document theme.

Alternatively, create a style based on the Normal style and set bold and italic and any other settings that you want. As long as you don't explicitly modify the font, it will follow the settings for the Normal style.

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional