Ok, but just because nothing is stopping you from buying a big bike on your beginner's license, it's most likely going to end badly, very soon.
Here in NZ and also Australia we have a graduated license system. It is governed by the power to weight ratio of a motorcycle and 'Learners' cannot punch above their weight.
It's supposed to keep people safe, but it's not an 'idiot proof' system.
When I turned 15 in 1973 we had a 'provisional license', you had restrictions but no restrictions on bike size.
I went for my practical test on my brother's Kawasaki 500 Mach 3. The cop saw it and said to me "Tell me that is NOT your bike!" I told him I had borrowed it for the test and he just shook his head and said "They call those things The Widow Maker, you take that home and I don't want to see you on that again but you can do the test on it today. Go SLOWLY ok??"
I'll never forget those words