The OP most probably is thinking the iPad Pro is not regulating the charge ~ hence why he/she is finding the iPad hot to the touch.
Question to the OP:- When you say ‘Hot’, define how hot this is?
My 12.9 iPad Pro gets ‘very warm’ when using the 29W charger but remains cold to the touch with the 12W charger.
This is to be expected as the 29W is pushing energy at the highest and safest charge rate, which in turn means you will get some form of heat build up.