Have you coded on larger code bases not written by you? Usually most of the time you read code instead of writing it. Sure you can add new code that adds smart pointers, but you still have to understand the exant code, at least to some degree.
I've done plenty contractual work on larger code bases that has C++98 to some extent. I will tell you what you will never truly understand the whole code base.
Sourcetrail does amazing job at explaining larger code bases. Check it out.
