ON:
#! /bin/bash
sudo vcgencmd display_power 1

OFF:
#! /bin/bash
sudo vcgencmd display_power 0

https://github.com/bugsounet/screen/blob/master/index.js

and

 async setPowerDisplay (set) {
    log("Display " + (set ? "ON." : "OFF."))
    this.screen.power = set
    this.SendScreenPowerState()
    if (this.screen.awaitBeforeTurnOff && !set) await this.sleep(this.screen.awaitBeforeTurnOffTime)
    // and finally apply rules !
    switch (this.config.mode) {
      case 1:
        if (set) exec("/usr/bin/vcgencmd display_power 1")
        else exec("/usr/bin/vcgencmd display_power 0")
        break
      case 2:
        if (set) exec("DISPLAY=:0 xset dpms force on")
        else exec("DISPLAY=:0 xset dpms force off")
        break
      case 3:
        if (set) exec("tvservice -p && sudo chvt 6 && sudo chvt 7")
        else exec("tvservice -o")
        break
      case 4:
        if (set) exec("echo 'on 0' | cec-client -s")
        else exec("echo 'standby 0' | cec-client -s")
        break
      case 5:
        if (set) exec("xset dpms force on")
        else exec("xset dpms force off")
        break
    }
  }

you should try each command to see what the results are
do this from and ssh connection to your pi, so you don’t have to fight getting the screen back on to work…

note that most of these turn off the HDMI port, and NOT the actual monitor.
many newer displays (since 2016) are energy star compliant and will display an upgly no input signal when the hdmi port is turned off… no way to override that

(and these displays will NOT turn back on when the hdmi port is turned back on)

ps… none of my displays will work with any of these commands

there are 4 different commands

tvservice - pi only turn off/on hdmi
vcgencmd - turn off/on hdmi
dpms - turn off/on hdmi
cec-client - turn off/on monitor

the 1st 3 will leave monitor on, and monitor may show a big ‘no signal/input’ screen for up to 15 minutes before powering off, this is energy star compliance

none of the commands that turn off hdmi can turn on the monitor after it powers off

I have two cec tvs, but one will turn off, but not back on, and other will turn on, but not off

soooooo. I use a hide/show all modules process