T ROC Is based on the Golf Leon and A3 platform...
looks good plastic are crap , But imo there big and comfy cars
That is not accurate. By "Golf/Leon/A3 platform" you mean the MQB platform but that is actually a group of different sub-platforms rather than one identical base that would indicate being the same car underneath. Otherwise one could state that the Seat Ibiza (MQB) is based on the Skoda Kodiaq (which is also MQB) and vice versa.
The T-Roc, Polo, Ibiza and Arona in particular, are based on the MQB A0 sub-platform which is the smallest MQB variant I think, and that is why all four of them offer identical cabin space as I believe the wheelbase is fixed but what goes before and after it (like engine bay and boot length) is variable.
Golf/Leon/A3 are the next "MQB size" and then Passat/Superb/Kodiaq are a further size up. All of the aforementioned cars are MQB based and have items in common, but size wise they are parts of different groups.