You need to create the bay window roof separately.
Revit roof secrets.
But i m not really sure if this is a best practice.
For creating complex roof it might be easier if you create separate roof then use join roof tool to join them later.
To turn a sloped roof into a flat roof select all roof boundaries purple lines and uncheck defines slope in the option bar.
Roof by footprint can be used for both flat and sloped pitched roofs.
2 activate slope to create a sloped roof want to create a sloped roof.
Revit then makes the wall meet the underside of the roof correctly.
Using shape editing tools.
Please like this video.
This is the easiest way to do it.
In the option bar make sure defines slope is activated for boundary lines.
Once again select the wall first 1.
Discover free revit bim objects for roofs.
I believe this tools are not design for this purpose.
We can use the same attach top base tool to tidy up this junction.