Hello @FaizanAhmad,

No, flow stages are not directly supported within the "Do the following in parallel" flow logic in ServiceNow Flow Designer. 

Refer below community post as well fyr:

https://www.servicenow.com/community/itsm-forum/flow-stages-are-not-available-for-do-the-following-i...

Please mark my response as Accepted and Helpful for future references.

Thanks