
Erk.
An unhandled baby.... at 2 hes a good year or 2 years away from being backed/broken and make that more like 3/4 years away from doing any 'real' work (needs time to mature and no horse is actually mature before around 10 years old, but cobs are slow to mature so you dont want them doing hard work before 5).
Being left in the field all summer is not particularly unusual, babies like this do no real work until at least 3 years old and then its learning about wearing saddle, bridle, carrying weight and balancing themselves and controlling their speed at walk and trot.
Being completely unhandled is not good though (although not uncommon), good horse breeders handle their youngstock and have them halter broken, so they will lead, teach them to pick up feet and be groomed and touched all over.
As an example to compare...
My friends rising 3 irish draught filly is leading in hand, leading from another horse, picks up all feet, is groomed all over, will wear saddle and bridle, long reins (being driven as if pulling a carriage but no carriage just 'driver' behind horse walking), loads onto horsebox or trailer, stables, can be turned out alone or in company, can be lead out alone or in company whether from the ground or mounted, stands for the vet or the farrier for her hoof trims, is fine with traffic, dogs, strange people, strange horses, weird objects.... she has been leaned over and sat on at this point but nothing more.
I would expect this cob to reach over 14hh but its very hard to say.
What i do know is she has got her work cut out, cobs have a reputation for being gentle giants but they do NOT end up this way by magic..... it takes solid hard work and without it they are just great big dangerous animals.
I hope she doesnt get bored because its going to be a good few years before she can ride it and take a lot of groundwork before she should consider backing it (even when it is old enough).