I can run xrandr now.
xrandr
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 800 x 600, current 1024 x 768, maximum 1024 x 768
default connected primary 1024x768+0+0 0mm x 0mm
1024x768 61.0*
800x600 61.0
cvt 1280 800
# 1280x800 59.81 Hz (CVT 1.02MA) hsync: 49.70 kHz; pclk: 83.50 MHz
Modeline "1280x800_60.00" 83.50 1280 1352 1480 1680 800 803 809 831
-hsync +vsync
sudo xrandr --newmode "CUSTOM" 83.50 1280 1352 1480 1680 800 803 809 831
-hsync +vsync
[sudo] password for akinn:
xrandr: Failed to get size of gamma for output default
X Error of failed request: BadName (named color or font does not exist)
Major opcode of failed request: 140 (RANDR)
Minor opcode of failed request: 16 (RRCreateMode)
Serial number of failed request: 19
Current serial number in output stream: 19
