No scaler (of the "render" section of dosbox's configuration file) seem to be taken into account under Linux. When setting output=surface, the dosbox window always has the original size, whatever the value of the scaler parameter (I tested scaler=none, scaler=normal2x, scaler=normal3x, scaler=scan2x and scaler=tv2x without any difference).
Note that output=opengl and output=openglnb successfully perform (non pixel accurate) HW scaling.
I'm running a Debian 12 Linux. I tested both the Debian packaged version of dosbox (0.74-3-4), and compiled dosbox from source (dosbox-0.74-3). The behaviour is similar.
Oh, I just noticed in depends on the game. I could observe the behavior mentioned in the description above on "The Last Express" game (from gog.com). I believe the game native resolution is 640x480.