How to check exactly what apt install [some package] is going to do?

I'm trying to compile a C++ project and got an error: xxx.so no such file or directory. In this case, normally I execute the command apt-cache search xxx and I can usually find a package name like xxx-dev, so then I simply execute apt install xxx-dev and it will be OK.

But in fact I don't know exactly what apt install xxx-dev will do. When we execute apt install xxx-dev, we can get some information about what would be installed, etc, but I want to know something more.

If I execute apt install xxx-dev, will it install more things than I need? For example, the error at the beginning told me that xxx.so was missing, however, when I execute apt install xxx-dev, I can usually see that many packages will be installed. Are all of these necessary? Is there a way to check exactly what apt install xxx-dev will do or to check what a deb package contains?