In CMD for Windows 10/11:
> at æ "ø"

Insert time instead of æ, for example like this: at 10:25 "ø"
Insert path to file instead of ø, for example this: C:\Users\Clumsy\AppData\Local\Programs\Python\Python39\myscript.exe
This also works for .ahk and .py scripts, and I think it works with others (such as .js and .bat)

import schedule
import time
import os

when= "20:11"
print("The computer will be shutdown at " + when + "")

def job():
    os.system("shutdown /s /t 1")

schedule.every().day.at(when).do(job)

while True:
    schedule.run_pending()
    time.sleep(1)