Forum Discussion
Change deafult font in SharePoint Online (modern experience)
Chris Gray You need to use SharePoint framework extension application customizer to inject the CSS to your modern SharePoint pages.
Following sample tells you how to inject the CSS:
https://github.com/SharePoint/sp-dev-fx-extensions/tree/master/samples/react-application-injectcss
Oh, and you have to import the fonts at the top of the CSS, from the url you want.
Udaybhanu Karmakar , solution you propose is not supported, even if viable. You should not use this to modify styling of areas you don't own. The purpose of this is to modify styling of your custom components. If you modify css of areas you don't own, it can break your modern site with some of the next Microsoft updates. Currently there is no solution to change fonts on OOB areas of modern sites. Its very unfortunate, but this is how it works with O365. Please use ms https://support.microsoft.com/en-us/office/uservoice-pages-430e1a78-e016-472a-a10f-dc2a3df3450a, so they have more inputs and use cases. User voice is unfortunately no more available.