Old 2DS doesn't support doubled resolution mode, so the top screen would look like the image below with the feature enabled.
This option should be grayed out in the settings menu on old 2DSes.
New 2DS seems to support it for some reason. (refer to https://libctru.devkitpro.org/gfx_8h.html#a1ffe33f6b3e9a61ee916997fc6cf6ace)
Core-2-Extreme
commented
3 years ago
Old 2DS doesn't support doubled resolution mode, so the top screen would look like the image below with the feature enabled. This option should be grayed out in the settings menu on old 2DSes. New 2DS seems to support it for some reason. (refer to https://libctru.devkitpro.org/gfx_8h.html#a1ffe33f6b3e9a61ee916997fc6cf6ace)