Ronaldo's physicality wasn't on a different level at 18/19 in my opinion, it was his sheer talent that set him apart at that age, yet he was not as good as Rooney for example at that age. Ronaldo developed into a physical monster a couple of year later.
And I'm not saying Chong is as good, just 30 minutes today was not enough for myself to make up my mind that he's not ready. He showed signs of nervousness, but also promise. Physically he looked fine to me, whether he can settle and play naturally is my concern.