I made a lot of different photos from landscapes and edited them with gimps g'mic, an effect called multi scale patch smoothing, this effect is not in every version of g'mic, you need one with the category testing, under testing there is another category called Iain ferguson, there you can find this effect.

the effect can be very time consuming on such large images!!! But it can make images look much more painted.

preview images are scaled down to 50%.