It is part of the operating system. You can either disable various power-saving measures. Or use the built-in shell command caffeinate. Or run a muted video looping in the background.
As a teacher, I was often in situations where a lesson would go on for a while with no computer interaction, and another teacher recommended Amphetamine. It worked well and I never discovered the shell command. I actually tried for a bit and never discovered a GUI option. Do you have a link handy?
Select either Battery or Power Adapter to make changes to how the system will go to sleep/turn the display off after a certain amount of time.
Sometimes Apple's design is so stuck in the 90s that I have a hard time wrapping my head around it.