Is it possible to grab the size of the form (window) of another application running to use as a "Region"?

Is it possible to define a Program or Windows as a region?
Is there a method to figure out this info?

Sikuli for automating but I am having issues using ti to confirm images due to the entire screen being a Region. It is easy to define regions on programs where the windows form is predicable but on VMs where I run my automated Test post builds, it has difficulty. I have also increased the Similarity to near 1.0 but some "screens" are 4k monitors where the margin is hard to predict.

Otherwise, this package is killer. it has really streamlined our workflow.