Yeah they're under something like Base Resources or Extra Assets I think in the DLC folders, but I wouldn't technically classify that as the RTP since they're not imported into the game when you create a new project. Hope that makes sense! :D
Viewing post in RPG Maker MV RTP Shoulder-Up Portraits comments
Indeed, after talking with you, I checked my RPG Maker MV order's download files and the SF characters' portraits are inside Base Resources and their upper-body pictures are inside Extra Assets, just as you said. :-)
Oh, I see, they are not automatically added into new projects so they are not part of the RTP, that indeed makes sense.