To be honest for a true pixel art style you are best putting in time and effort and using something like Procreate and tracing other a layer of your reference image. Though for a quick and less painless method you can use AI and Photoshop
Get your reference image from a screenshot in game
Remove the background using something like Magic Eraser
Run it through something like Gemini until you get close to effect you want
You will never get an AI Model like Gemini to get a true clean pixel style though, so this when tools like Photoshop come in
This is just a quick method though as mentioned results make vary. You are best doing it manually though to be honest with pixel art
