Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hi Vegard,
In SharePoint Online, the PDF files are set to open in the PDF reader by default. If you have adobe PDF reader add in installed on your browser, the PDF files will be opened directly in the browser. We cannot use Word online app or the WopiFrame URL to open PDF files. I would suggest you submit your feedback to our SharePoint Online User Voice. Your providing feedback is the best way to perfect our products and services.
Thanks for your understanding.
Regards,
Ran