I am working with a customer and it was a great question. I was trying to find the exact answer.
The Code requires a minimum of 18” clear from the bottom of wood floor framing to the ground. (See ICC Figure 403.1 (3).)
I remember seeing that the bottom of beams can’t be within 12” of the ground, but I can’t find that requirement...maybe that was in an older code.
Btw, don’t forget you need an 18”x24” crawl space access if you go through the floor and 16” x24” access if you go through the perimeter wall. (See ICC R408.3.)
Also, you need 1/150 area ventilation without a vapor barrier and 1/1500 area ventilation with a vapor barrier. (See ICC R408.1) There is an exception for eliminating crawl space vents on one side.
There is no direct answer as far as building codes are concerned.
A crawlspace is a designated area under the floor that allows for your house to not get flooded. That it allows you access to plumbing and electrical... or whatever, that is not its innate purpose nor is there any sort of building requirement around it. Since there is no requirement, there cannot be a height requirement.
However when getting a loan, there are often crawlspace requirements and this can be by agency and/or by area of the country. For FHA loans for example it is a given that you need to have 18" of crawlspace. I have had to dig out parts of "crawlspaces" before to meet this requirement.
If you are building a home without a basement and it is raised - not slab - 18"+ makes sense. If you are going to raise the house you might as well be able to make electrical and other changes easier and to push further away from flooding issues. Why have 10" crawlspace that you can't even use if flat on your back?
In Europe there is apparently safety regulation that forbids companies working in crawlspaces lower then 60 cm. I found out when I had a gas-man come into my house for a quote. He told me he could not legally do the job.
I searched the internet and found a reference in a Dutch site to "NEN 3140": https://kennisbank.isso.nl/kenniskaart/veilig-werken-in-kruipruimten (Which means: "Safe working in crawl spaces")