At very basic level, is the brush outline enabled in Edit -> Preferences -> Image Windows -> Mouse Pointers ? screenshot: https://i.imgur.com/r7EhKqu.jpg
Then there are the various modes none - aligned -registered - fixed which determine how the source follows the active clone brush. All in the docs https://docs.gimp.org/2.10/en/gimp-tool-clone.html and it is worth reviewing this for aspects such as transparency and the bit at the end about effects.
At an extreme, when cloning from layer-to-layer or image-to-image and the source is hidden, temporarily go into Gimp multi-window mode. https://i.imgur.com/SK6dPHW.jpg
Then, there is a new tool, seamless clone, it is there in Gimp 2.10 but needs enabling. https://i.imgur.com/wn6OOl2.jpg Experimental and a bit flakey. Takes a selection and merges the clone colours with the underlying image. I think in PS this is 'smart clone' or something like that.
edit: But always better to forget about how PS works for there lies insanity
Then there are the various modes none - aligned -registered - fixed which determine how the source follows the active clone brush. All in the docs https://docs.gimp.org/2.10/en/gimp-tool-clone.html and it is worth reviewing this for aspects such as transparency and the bit at the end about effects.
At an extreme, when cloning from layer-to-layer or image-to-image and the source is hidden, temporarily go into Gimp multi-window mode. https://i.imgur.com/SK6dPHW.jpg
Then, there is a new tool, seamless clone, it is there in Gimp 2.10 but needs enabling. https://i.imgur.com/wn6OOl2.jpg Experimental and a bit flakey. Takes a selection and merges the clone colours with the underlying image. I think in PS this is 'smart clone' or something like that.
edit: But always better to forget about how PS works for there lies insanity