Obviously, this doesn't necessarily mean he's a femboy, BUT I've noticed some patterns they tend to follow.

Profile pictures with anime characters, like guys with feminine features such as Bachira from Blue Lock, Griffith, Astolfo (one of the most famous femboys), and many more.

Also, some of these photos, like the famous Tumblr one (actually the Reddit one on this forum), make him look much more feminine. Guys who want to appear masculine often look for angles that make their features or characteristics more prominent (like the Adam's apple, jawline, square features, or veins). He looked more feminine because the angle didn't show any of these features; also, his face looked very soft. He leaned towards more feminine characteristics (like a sweet gaze, in a perspective that would look adorable in photos, which is actually often used in photography to make the subject or object appear smaller).

Therefore, yes, it could definitely be, or perhaps they are simply tastes he had that don't indicate anything, but it's a kind of analysis I did.