and BTW: I started using J option to post in feed and stories but realized that the stories output is terrible.
So is it needed to have 2 different images? one for feed (1080x1080) and another one for stories (1080x1920)?
and how to manage posting them in the same campaign?
Yep, most definetly you need two different campaign, as the format is different. I don’t have access to my laptop and won’t have for some time, I am currently on mobile. You can go to BHW in the download section and spend some time searching. It is something like 210 Instagram Stories Templates. I don’t know where excatly it is myself so I would be searching as well