The after parameter is just still there for people who mix this library with curl etc. there is no need to specify it.
first basically just specifies the batch size the library fetches with.
With normal use you dont have to specify either of those.
However the docs are not 100% clear on that (although it does explicitly specify in multiple places that it auto paginates). Thats why I also still have this issue open: specify the use of first and after in docs · Issue #235 · Teekeks/pyTwitchAPI · GitHub
To summarize: you have to change nothing to access all values, the library handles pagination.