Flow or Workflow for a SharePoint doc library where approval is required for a checked-in doc

Hi All,

Does anyone know how to create a Flow or Workflow for an online SharePoint document library where approval is required for a checked-in (major) document? We are working on a new experience, Online SharePoint site.

I have done this before on a SharePoint 2010 on-premise site, but I cannot get it working for a new SharePoint online document library. The approval email that is sent out to outlook online thinks you are using Outlook 2010 and there are reject approve buttons on the outlook menu, but there is no button within Outlook online.

I hope you can help
Alan