The hope with every incoming draft class is that the early round selections can be immediate contributors. Even those taken in the middle to late rounds can potentially help out on special teams.
However, while that's the hope, the draft is also meant for planning ahead because teams should be selecting players based on who they believe they will become, not who they are on draft night.
In part, the Green Bay Packers find themselves in a world of hurt at the wide receiver position because they didn't plan ahead. Sure, they spent three picks on receiver in 2018, but none since then.