Is it possible to change the text size of lables?

gwenview 24.0.2
gnome 46.0 wayland
linux 6.8.9
display: 3840x2160 28"

Because the display is UHD, the font size shown in Gwenview is quite small. Other apps use Gnome’s text “scaling factor” to increase the font rendering; GV apparently does not.

Is there an option within GV to increase the font size? (I also note that none of the settings options are functional.)

KDE apps assume that the environment around them has taken care of the scaling. In your case it has… but it sounds like it’s failed to set the correct environment variables for Qt apps to scale themselves. As a result only GTK apps are betting scaled. This is a GNOME bug; please report to them at GNOME / Settings · GitLab. Thanks!