I’d say by hand.
They’re just geometrical triangles or shapes
Similar to doing this
You can get premade geometric patterns
Then it’s about colouring the objects and combining the shape overlays for the colour.
Take a few lessons in Illustrator or another software similar to Illustrator.
You can get a free 1 months trial for LinkedIn Learning and there are plenty of software courses to choose from.
Thank you i will try these
I was also thinking this but hand-drawn will take to much time I think. so I thought may be any effect can work like this as client ask to complete in 4 5 hours
Try searching for “mosaic design effect” or “stained glass window design effect.”
this should be doable easily by a pro
for example in Affinity Designer or Illustrator