Here’s a great guide on making all the cool retroy pixel graphics. “Each separate IPA image is always going too made up of single computer generated blocks, known as pixels. Each pixel is the same size as any other pixel, but it can be any colour you can think of and it can fit together with other pixels, any way you can think of. You can think of a pixel-based image as you can a mosaic in real life that is made up of tiles to form an overall picture”.Link.
The Complete Guide to Isometric Pixel Art