Some building types in some jurisdictions do not require engineered plans.
My 24x40x12 shop did not require plans at all, just a drawing of the size, location on the lot, and clarification the type of materials to be used.
Inspections at each stage made sure that code was being followed.
Only the trusses were an "engineered" element, and they always come with certification and engineering drawings anyway.
If yours has living space, or a second story room, they may require actual plans.
At a previous home, I did a room addition, above the garage, and the building department accepted my AutoCad drawings as plans.