How do I have a PowerPoint auto start and auto full screen within SharePoint 365

Hi @CGimro ,

You can change the URL to show the file in presentation mode by changing the page.

There are two workarounds for this：

1.Change the Doc.aspx to wopiframe.aspx

Let me give you an example:https://domain.sharepoint.com/:p:/r/personal/account_onmicrosoft>com/_layouts/15/Doc.aspx?sourcedoc=%7BFBF4CB1F-003F-40E3-81DF-06DDFD364894%7D&file=Team%20Meeting%2020230221.ppsx&action=edit&mobileredirect=true

Change URL (fullscreen demo mode):https://domain.sharepoint.com/:p:/r/personal/account_onmicrosoft>com/_layouts/15/wopiframe.aspx?sourcedoc=%7BFBF4CB1F-003F-40E3-81DF-06DDFD364894%7D&file=Team%20Meeting%2020230221.ppsx&action=edit&mobileredirect=true

2.Change the action=edit&mobileredirect=true to &action=embedview.

Example:https://domain.sharepoint.com/:p:/r/personal/account_onmicrosoft>com/_layouts/15/Doc.aspx?sourcedoc=%7BFBF4CB1F-003F-40E3-81DF-06DDFD364894%7D&file=Team%20Meeting%2020230221.ppsx&action=embedview

Reference: https://answers.microsoft.com/en-us/msoffice/forum/all/open-powerpoint-from-office-365-in-presentation/51d10939-f2d4-4be5-916f-9b1409381475

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