Drawing a simple rectangle layer?

[PixLab]

(04-09-2022, 09:42 PM)tmanni Wrote: 2 ways:
1) when you create a new layer, you can specify its width and height in the dialog window
or
2) if you have an layer too big for your needs, create a selection and do menu Layer > Crop to Selection

just adding 1 more way
Very similar and as simple as tmanni's answer
Once you've filled your selection and have by accident de-selected(no active selection) Main menu do Layer ➤ Crop to content will do the trick as well