Gimp is not the best in the world for your request.
There are already standard brushes - bristles - acrylic that you should try using different FG / BG colours and a brush dynamic such as Random Colours or Confetti.
You can make your own animated brush in a Gimp Image Hose .gih format This is an example of that 5 layers - grayscale image - exported as a .gih See the attached, unzip put in the brushes folder.
...and in action a 40 second animation. https://i.imgur.com/aiaYEzZ.mp4 Not exactly oil painting. Please have a go at making your own, Gimp is great for experimenting.
For oil painting effect, as an alternative, you might look at the MyPaint program https://mypaint.app/about/ or if you want to spend some cash, something like ArtRage.
There are already standard brushes - bristles - acrylic that you should try using different FG / BG colours and a brush dynamic such as Random Colours or Confetti.
You can make your own animated brush in a Gimp Image Hose .gih format This is an example of that 5 layers - grayscale image - exported as a .gih See the attached, unzip put in the brushes folder.
...and in action a 40 second animation. https://i.imgur.com/aiaYEzZ.mp4 Not exactly oil painting. Please have a go at making your own, Gimp is great for experimenting.
For oil painting effect, as an alternative, you might look at the MyPaint program https://mypaint.app/about/ or if you want to spend some cash, something like ArtRage.