How to find 4k and 6k res images. (Patreon)

I didn't think that I'll need to create such a post, but I've had several people asking how to find 4k and 6k images. Here is a small tutorial that will help to find high-resolution images. 

Please notice that this reward was added at the end of 2020. If you can't find a 4k or 6k res image this means that it doesn't exist. 

Hope this will help. Thank you!