If you selected a color mode, it will resume outside of night hours.
Your phone can automatically filter out blue light and adjust screen colors to warmer tones at night, making it easier to view and read in dim light. You might even fall asleep more easily.
Touch Schedule, then:
To adjust filter intensity, open quick settings, touch & hold 
To temporarily switch back to regular colors from amber, open quick settings and turn off 
To stop automatically changing to amber, select Settings > Display > Night Light > Schedule > None.
To help you wind down at night, your phone can change to grayscale (black and white).

To temporarily switch back to regular colors from grayscale, open quick settings and touch 
To stop automatically changing to grayscale at night, go to Settings > Digital Wellbeing & parental controls > Bedtime mode > Customize > Screen options at bedtime and turn Grayscale off 
If colors don't appear as you expect, troubleshoot the issue.