Is there any tool to have/look the C++ interpretation from a template form syntax to its expansion/substitution before it really gets compiled to object/binary?

C++ Insights tries to do something like that:
https://cppinsights.io/s/c9be9f45 <-- press the play ▶️ button to view the result

Note that it doesn't only handle templates. It will also transform auto, lambdas, range-based for-loops, structured bindings, etc.