If you are editing files inside a package, you can generate a tags file for definitions inside that package.
More useful, IMHO, is the general solution of jumping to the definition that would be resolved by the python interpreter, regardless of location. For that, the key binding will depend on the plugin. For `jedi-vim`, you use `<leader>d` [0].
Incidentally, if you're new to using VIM as a python IDE, also note the value of `jedi-vim` providing Python docstrings via the standard VIM keybinding `K`. This is also mentioned in [0].
More useful, IMHO, is the general solution of jumping to the definition that would be resolved by the python interpreter, regardless of location. For that, the key binding will depend on the plugin. For `jedi-vim`, you use `<leader>d` [0].
Incidentally, if you're new to using VIM as a python IDE, also note the value of `jedi-vim` providing Python docstrings via the standard VIM keybinding `K`. This is also mentioned in [0].
[0] https://github.com/davidhalter/jedi-vim#features