I followed the basic structure of the mandala Helen demonstrates, but changed quite a few details.
Since I am using Affinity Photo, I didn't have Photoshop gradients to choose from, so I created a simple radial gradient.
In Affinity Photo using the Darken blend mode with the gradient colours white areas of the mandala.
The Lighten blend mode colours black areas of the mandala.
The Difference blend mode colours both white and black, resulting in greater complexity.
I was delighted to discover how easy it is to invert black and white. This seems to work the same way in Affinity Photo as in Photoshop.
The Lighten blend mode again colours black areas of the mandala, but the black areas are now opposite from before the inversion.
The cracked paint texture Helen provided is great! To experiment with it I went back to my original version of the mandala, before inversion.
In the following example the blend mode for the gradient layer is Hard Light and the blend mode for the texture layer is Hue.
In the following example the blend mode for the gradient layer is Hard Light, and the blend mode for the texture layer is Contrast Negate.
I discovered other blend modes that I like, but these examples show a range of possibilities from fairly obvious to unexpected. Blend modes in Photoshop may not give exactly the same result even if they have the same name.
You may like to see how I used this mandala in my project for Teela Cunningham's class Watercolor Textures for Graphic Design, where the background is watercolour texture rather than a gradient: