GameMaker released a free asset bundle for their subscribers. However it's pretty raw and needs an image processing tool to combine all parts. This tool makes it easy to combine, preview and export. But it's only for GameMaker users. Users of other engine developers may not benefit from this.
https://aliustaoglu.itch.io/portrait-maker-for-gamemaker-bundle
Please note that bundle is free but only if you're a GameMaker subscriber which is not free. I cannot re-distribute this bundle. Therefore you have to download this from your yoyogames account and copy the folder under this tool. Then you'll be able to generate hundreds of characters like this one:
Bundle should be downloaded from: