Hi @Audi86 ,
1.Create a list or library in the site content and create custom forms.
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2.Enter site pages, create a new page, and add InfoPath Form Web Part.

3.Or publish the form directly to the SharePoint Online form library after completing the form design in InfoPath Designer 2013.
Reference: Publish InfoPath Form to SharePoint Online Office 365 Step by Step Tutorial
If this is helpful please accept answer.