Baseline (Widescreen) Solution & Issues
The Game only offers 16:9 resolutions till 2560 x 1440. For 16:10 or 4:3 resolutions a Hex edit is necessary.
Hex edit resolutions: Go to --> ...\Steam\steamapps\common\Disney Infinity 3.0 Gold Edition\DisneyInfinity3.exe
Look for 80 07 00 00 38 04 and change it 80 07 00 00 B0 04(1920x1200) for example - see here for your des. resolution.
Ultra/Super-Wide (21:9/32:9) Specific Solution & Issues
Same solution as in Widescreen - Look for 80 07 00 00 38 04 and change it 70 0D 00 00 A0 05(3440x1440)
Eyefinity / Surround Specific Solution & Issues
Same solution as in Widescreen - Look for 80 07 00 00 38 04 and change it 80 16 00 00 38 04(5760x1080)
4k UHD Specific Solution & Issues
Same solution as in Widescreen - Look for 80 07 00 00 38 04 and change it 00 0F 00 00 70 08(3840x2160)