You do not need the DLCs, but your build search might require you to look for build posts earlier than mid-year 2017? (iirc). A lot of the old forum was moved over, and this newer forum is much easier to search, which is a good thing. However…I`m not sure if the older collections are updated.
You could start your search here old build guide
I believe that there are some of the updates (updates, not dlc) have tweaked some of the base-game gear for the better, as well. These updates possibly address some base bugs (I don`t know.) You could download these online for free but you could also just play base game without updates too.