Eye-dropper like tool for texture of trail

I’d like to be able to ‘draw’ more of the trail that can be seen in the above picture in between the two trees.
I’m doing data augmentation for ML, so I want to have the same features but maybe add another one in a different direction for example, with a loop etc…

Is there some sort of tool (something similar to the eyedropper), where I could have a pen that would draw this?