Oh most of us that change it so often make the iconen ourselves.
If u ever find an image u want to be an icoon I could always make it for you. XD Ive made probably near a thousand of so iconen door now. I really enjoy making them
But essentially u zoek up whatever u want an icoon of, u find an image that u think would make a good icon, take it to some kind of editting software (or paint if u dont plan to do much to it), and at the very least, crop the image to be the size u need it to be (square)
u can get meer creative with it the meer your practice too
I usually used
link to pas aan and crop and all cause its like Photoshop but online free and has no downloads. Not as good as Photoshop but definitely plenty enough.