Sharepoint - Set Modern Page as a Home Page

You can set a modern page as the home page. Go to the pages library. Select the desired page, on the top click ... you will see 'Make homepage' button.

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Other way is right click on file for options and select the "Make homepage" option. enter image description here

Make sure that your Site Pages library is using the New experience. You can enable it in Library settings > Advance settings > List experience.