There are different versions There are some that are basically cyclocross bikes with slacker geometry and then there are some real beasts out there. Gravel bike tires vary from .5 inches to 3 inches! It is extremely varied.I used too ride a lot of old rail road beds on my bmx bike too get places and recently did about 2 miles of it on my klunker. I’m guessing these bikes are built for something finer because I can’t see building any real speed on that large loose stone
Then, there is THE BEAST!