If you really need a street legal bike because of the headlight and taillight, I suggest this bike.
https://www.orionpowersports.com/ori...embled-tested/
Nearly full-size, but shorter seat height, and even though you will be wearing boots, a lower seat height will give you far more confidence being a new rider.
If you do not need lights, then I suggest any number of pit bikes in the 125cc-150cc range to learn on (I do suggest a manual transmission to learn how to shift), with the bonus being very low price point. As someone pointed out, you might find some in the few hundred dollar range which will be a bonus.
That being said, you might want to consider a semi-automatic transmission due to your age. You are only 12 so have a few years until you are able to legally ride on the street, so practice makes perfect.
A dual-sport is not necessarily recommended unless you are really riding on trails as opposed to dirt bike riding. The dual-sports can take abuse, but up to a point and are really not designed as 'dirtbikes'. The Orion I linked to is kid of technically a 'dual-sport' due to having full lighting, BUT is more of a dirt bike with street lighting, and I do feel you should be leaning towards a dirtbike at this point being a new rider. When you are going to street ride, then I suggest a proper dual-sport like the Brozz.
Let us know what you decide.
