DisplayLink Drivers do not support HiDPI above 1920x1080 for a M1 (assuming your using a M1?). This has been an outstanding feature request since last year. You can vote for it
here.
In regards to can anything be done to overcome the limitation, the only available solution that I am aware of appears to be to acquire a single monitor with enough real estate space and then drive it directly from the M1. The M1 itself provides HiDPI resolutions above 1920x1080.