You can add new brushes to Affinity Photo such as adding arrow brushes, grid brushes, weird brushes and many more. You can also modify the spacing for the brushes as well as size and rotation as well as add some randomisation to the strokes such hue and saturation etc - here is a tutorial by graphicxtras.com / Andrew Buckle on the subject You can find the arrow brushes on Arrow brushes
By Andrew Buckle. Photoshop custom shapes, Illustrator symbols, plug-ins, brushes, styles, picture tubes, gradients and many more for Photoshop and Photoshop Elements and Affinity Photo, Affinity Designer, Krita, Paint Shop Pro and Painter.. as well as fonts, patterns, textures etc for many others. Programming as well as designs and arts and scrap booking and a little more