InfoPath Dev

Does anyone know how I can use a workflow to change a users permissions in a sharepoint library with or without using InfoPath. 

SharePoint Online? What about using Power Automate? There is a SharePoint HTTP Request action that I've used in the past for modifying permissions.... This sample is a bit old (so the screenshots / steps may not match what is currently available), but may get you started: https://noellawlor.wordpress.com/2018/01/18/setting-sharepoint-item-list-permissions-with-flow/

Oh, here is something more recent that may also help you: https://docs.microsoft.com/en-us/sharepoint/dev/business-apps/power-automate/guidance/manage-list-item-file-permissions