You use elaborate to describe something that is very complex because it has a lot of different parts.

Elaborate plans, systems, and procedures are complicated because they have been planned in very great detail, sometimes too much detail.

Elaborate clothing or material is made with a lot of detailed artistic designs.

If you elaborate a plan or theory, you develop it by making it more complicated and more effective.

If you elaborate on something that has been said, you say more about it, or give more details.