How to change resolution of the internal display on a Macbook?

Yes I know that, I could have phrased that differently. Of course you can't change the amount of pixels the screen has, but you can change the amount of pixels the gpu renders, which is what im trying to do.

For example if the screen is 4K and I set the resolution to 1080: All the pixels on the screen will still be used yes, but the gpu will only render 1080p resolution and each square of 4 pixels on the 4K screen will display the same pixel from the 1080p image which is shown.

When changing between the scale options on the Macbook I don't think it actually changes the pixels which are rendered, it only scales the OS itself to look bigger, but still rendering the same amount of pixels which means no gain in performance of battery life.

Thank you ManJor for you answer. I am aware of the settings that the page you linked to are showing, but that is not exactly what im looking for.

As far as im aware that scale setting simply changes the scale of how big text and program windows are shown on the screen, but the resolution of the screen stays the same. That is why on the default scale option it says "looks like 1792x1120" instead of the resolution of the monitor which is 3072x1920.

I want to be able to change my resolution to for example 1680x1050 instead of the default 3072×1920. This way the gpu wont have to render such a high resolution image output which requires more power.

I am not even sure if this is possible on Mac OS... Would be way better if Apple just had a button named "Show Advanced Screen Settings" which immediately gives you a list of resolutions to pick from and the different refresh rates the monitor is able to run, instead of hiding those basic features behind weird key combos or not giving us the option at all.

I'll check out SwitchResX, thanks :)