like you select a part of the image and the changes apply only to that part?
I don’t think that there is. I have to move the image to Gimp, and use a layer mask to apply local changes. I’d love to see layer masks implemented on RawTherapee.
There’s a special build, called Local Lab, which allows to apply some filters on parts of the image. Look in the forum and you’ll find it.
It’s not using masks, but control points and areas under the control points.
Edit: look here Local Lab build
darktable has masks for almost all modules