Large-scale; on a grand scale. Describes something that requires extensive preparation or equipment (na-adjective, can also be used as a noun).
そのイベントは大掛かりなセットが必要だ。
That event requires a large-scale set.
大掛かりな工事のため、道路が長期間閉鎖される。
Because of large-scale construction work, the road will be closed for an extended period.
映像制作には大掛かりな機材が投入された。
Extensive equipment was used in the film production.