here my Workflow for faking acrylic paintings in Affinity Photo using FotoSketcher(Freeware).
I'm using FotoSketcher(.com) for the brushstroke effects. (PhotoArtist, AutoFX AutoMagic or Topaz Impression should work too, but not tested)
Form the source image i generate 4 images with different minimal brush sizes, normaly 40, 20, 10 and 5. FotoSketcher settings: Painting 7(Gemälde 7).
Have a look at the attached afphoto file. (It's simple, but complicated to explain)
The images with thick brush strokes(40, 20) are used for the background and the remaining two images(10, 5) are for the subject und fine details.
In Affinity Photo (or Designer) the image with bigest strokes gets loaded and used as main background and the others used as layers on top.
My next step is adding layer masks and inverting (strg + i) them. A white brush on the mask is used to paint back the details. The Layer with fines strokes is only used for the face/eyes and other important details.
Affinity Photo only: Now i combine the layers to a new layer for a paint effect. Dublicate the layer and apply "find edges" filter. Invert it (strg+i) and use curves to intens the borders. These two layers are needed for Lighting-Live-Effect and texture settings and notice the layer blending settings.
Because i used a bw image as sample, i added some colour with extra layer ("Basecolour").
The last three layers adding some artistic feel to image.
Colour variation layer: Colour variation are often used in paintings to fake details and add more life to a images.
Warm layer: Add a warm orange colour tint to sun lit surfaces.
Cold layer: To add a blueish ambient tint to some shadows.
You can use load you own brush as image in FotoSketcher. In Brush.zip are my test brushes.