This is an overlay mosaic pattern worked in US terminology.
The pattern contains a square that can be repeated to the desired width and length of your scarf.
You will need to know the basics of mosaic crochet but there are tons of videos for beginners on YouTube.
Mosaic crochet is a dense crochet, no “holes” so is ideal for blankets, rugs, runners, cushions, etc.
You can use a variegated/print/cake yarn and allow the yarn to change colour on its own or you can use two separate colours to create a contrast in the pattern.