if the intent is to have 3 screens with all different content as most menus do, you can also arrange your screen so that you have 2 at the top and 1 at the bottom all in1920x1080 resolution in screen type and in windows settings - they can then be arranged physically in any manner you want.
if however your intent is to use the screens as one continuous division for videos for example, then you do indeed need them arranged horizontally which will at times go beyond 4096x4096 resolution which we currently cannot accommodate.
we do have plans to extend the limit to 8k but the devs are focused on addressing other issues in our existing core features thus we would like to ask for your patience. we will have more info on this in the coming months.
best regards
-ADMIN