Tongue weight is a function of the trailer load and how it is loaded.
If you could hang a big motorcycle on the back bumper your tongue weight would go down. If you mounted it to the hitch frame it would go up.
How much stuff you add to your TT when prepared for a trip impacts the tongue weight. From the factory my TT is advertised at 5004 lbs with 460 lbs tongue weight. In the real world my loaded TT weighs closer to 6400 lbs with just under 700 lbs. on the tongue.
In general, 10 to 15 percent of the TT weight is a good tongue weight estimate.