New Reddit developer has release a tweak named SleepAnywhere for jailbreakers, here is the detail:

SleepAnywhere

Is your phone to large for you to reach your lock button? Are you tired of clicking your lock button? No worries, now you can sleep your device anywhere you want. Just by using gestures. This tweak will include pinching your HS or LS to lock your device, double tapping your HS or LS to sleep your device, and double tapping your status bar; long pressing it; swiping left or right to lock your device.

Download the tweak in https://repo.auxiliumdev.com/ 

Also, join the Auxilium discord if you have any questions.