The only site I know of that would vaguely fit the bill is https://openclipart.org/ https://openclipart.org/. However, it doesn't appear to support searching by

The only site I know of that would vaguely fit the bill is https://openclipart.org/ https://openclipart.org/. However, it doesn't appear to support searching by image type or by dimension and as far as I can tell, it cannot be 100% guaranteed that you will have all SFW images.