Descriptions for each customizable feature:

Brushstrokes:

• Brushstroke scale - Customize the size of the brushstrokes relative to everything else. This is useful to control how stylized the painting looks. Any number greater than 0. Default: 1.
• Brushstroke orientation - The angle at which brushtrokes appear. Ranges from -1 to 1. -1 being horizontal and 1 vertical brushtrokes. Any number in between is a random orientation for each brushtroke, biased towards horizontl or vertical depending on the number. Default: 0 (random orientation for each brushtstroke).
• Large noise - Randomness of brushtrokes. Default: 0.2.
• Medium noise - Randomness in between brushtrokes (smearing effect). Default: 0.2.
• Small noise - Rndomness of overlapping brushstrokes (blurring effect). Default 0.16.

Paint Texture:

• Brushstroke strength - Strength of brushstroke bumps. Default: 0.333.
• Canvas strength - Strength of canvas bumps. Default: 0.333.
• Canvas scale - Scale of the canvas relative to everything else. Default: 0.5.
• Level of exposed canvas - Amount of randomly exposed canvas. Ranges from 0 (no canvas) to 1 (most canvas showing). However, greater values can be used to fully expose the canvas. Default: 0.5.
• Paint wetness - Wetness of the paint, controls clearcoat and roguhness of the material. Ranges from 0 (dry) to 1 (wet), however higher values can be used. Default: 1.

To use a single RGB base color, disconnect the image node from the Principled BSDF (connected to the base color input) and select the color there.