Select base SDXL resolution, width and height are returned as INT values.
If using older model SD 1.5 or SD 2.1 use the base adjustment dropdown. This will adjust (reduce) the base_resolution to suit the model. ie. 1024 (SDXL) will equal 768 in SD21 and 512 in SD15.
Resolution list based off what is currently being used in the Fooocus SDXL Web UI

Installation

# Change to the directory you installed ComfyUI
cd pathTo/ComfyUI

# Change to the custom_nodes directory
cd custom_nodes

git clone https://github.com/bradsec/ComfyUI_ResolutionSelector.git

# Restart ComfyUI

The new node can be found under: Add Node > utils > Resolution Selector (w x h)