Could you share more details on your scenario?
Do you want to send out a report every week? If yes, please try to use the trigger Recurrence.
Please get more details on Recurrence at here:
What do you want to report from Office 365? You may try to get events, contacts, emails, etc. then send out an email with the details of the events/contacts/emails. The following doc for your reference:
Please try it on your side and feel free post back if you need more help.
I don't really understand what "Flow" has to do with this, but maybe check out this link and see if one of these reports will give you what you need.