This Lora tries to strengthen a more oil-like style. I can somewhat get this without a Lora but it was very inconsistent and I'm not perfectly happy with the Lora either, but it seems more consistent than without and I got some interesting results.

Trigger word is painterly, but I recommend also using traditional media and perhaps film grain, and add a bit of token weight on them. Use a DPM sampler instead of Euler as this helps put in a bit of randomness to enhance the brush stroke effect.