The reason we write software is to save us time :-). The way I do it is :

- download (free) video game tiles

- upload them to https://www.pixelartcss.com/ to turn them into CSS

- use this tool (kindly made by thecodingfox a few days ago) to place the tiles on a grid and create the whole image from the CSS returned by pixelartcss : https://www.thecodingfox.com/interactive/pixel-world-editor/