At the end of the page before the page where you want the numbering to change, you have to insert a section break. Then go to the footer (or header) and insert a page number field, for example by pressing Alt+Shift+P. Click Insert > Page Number > Format Page Numbers to open the Page Number Format dialog box and select the page number format of your choice. See also Numbering Front Matter (Ribbon).

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional