SetScreenResolution | small Windows utility to change the screen | Command Line Interface library

You have two issues preventing you from getting what you want.

First, the way you parse integers on your Arduino code is expecting a separator. It reads until it finds something that is not a number. To fix that just add spaces on the strings you send, or colon or whatever you like. Otherwise Serial.parseInt() will not be able to read anything because you are only sending numbers from Python.

Second, you cannot read in Python with serial.readline() if you use raw write (Serial.write()) from the Arduino. Again, Python is expecting a line terminating caharcter. To fix that, add \r\n to the string you send or use Serial.println() instead. If you don't want to add those terminating characters you can read bytes in a loop until the buffer is empty.