In the US at least, you need a CDL if you drive a vehicle with a gross vehicle weight greater than 10,000 lbs (4536 kg). The 2022 GMC Hummer EV weighs a whopping 9,063 lbs (4111 kg) so that's probably the largest vehicle a regular person would be able to buy.
That only matters if you're "for hire". I'm not aware of a single state or province where you can't drive a 45 foot long tour bus RV towing a double car trailer on a regular license. You can legally b-train trailers in lots of places. Giant truck + huge trailer + cargo trailer full of quads and side by sides is totally kosher.
Edit: I can go buy a Ford F750 and drive it like a pickup truck if I want. The Hummer is not nearly the biggest vehicle a normal person can buy and drive
It is 3500kg in Germany for your regular driver's license (unless you got yours in the distant past) so that is probably one market that limits it a bit more here in the EU.
Commercial motor vehicle: means any self-propelled or towed motor vehicle used on a highway in interstate commerce to transport passengers or property when the vehicle—
(1) Has a gross vehicle weight rating or gross combination weight rating, or gross vehicle weight or gross combination weight, of 4,536 kg (10,001 pounds) or more, whichever is greater; or
(2) Is designed or used to transport more than 8 passengers (including the driver) for compensation; or
(3) Is designed or used to transport more than 15 passengers, including the driver, and is not used to transport passengers for compensation; or
(4) Is used in transporting material found by the Secretary of Transportation to be hazardous under 49 U.S.C. 5103 and transported in a quantity requiring placarding under regulations prescribed by the Secretary under 49 CFR, subtitle B, chapter I, subchapter C.