Leonardo.ai has an image to image generator, and you simply have to use some of the settings below with the prompt:
((concrete, 2D))These are the main settings you should look for. I highly recommend reusing the best possible texture generated by putting it into the tabbed panel labelled Image Guidance (see the second picture below) and playing around with the strength value. You may also upload a texture and try to improve its visuals using Leonardo.
Finally, you can copy it to a clipboard or download the texture.
Note that Leonardo.ai is mainly a subscription service and offers limited free credits.