How to set entire game resolution?

How can I set the entire game resolution?

For example a game like celeste. Where the resolution is 320x180 and not just upscaled assets.

Is there a way to render to a texture and show that or is there something simple I can set in config.lua?

Never mind I figured it out! Works perfectly. I can render 1 group at 320x180 (adjusted for device aspect ratio) and then render the ui on top of that at native res. Thanks guys!