You can have a 3D look, derived from 3D models, but bake them into 2D sprites. You can use 3D models, but 2D mechanics (colliders, triggers etc). You can use sprites (2D) and arrange them in 3D space.
You need to keep the graphical representation, 2D or 3D, apart from the mechanics. Then ask yourself these questions:
— where’s your talent or interest: 2D or 3D. Can you model, animate in 3D or better in 2D? There are also hybrids, like skeletal 2D.
— what are you trying to do exactly? Do you need 3D? (generally, a dimension fewer is a dimension you don’t need to worry about). If you want to use the third dimension in top down, you’ll have to worry a lot about camera movement. Keep in mind that Unity is never truly 2D. Even in 2D projects you can use height, i.e. distance from the ground plane in top-down.
Generally, YouTube is filled with Zelda 2D tutorials, and most (all?) I’ve seen are 2D like the original. Check the usual suspects, Brackeys, and Blackthornprod (he generally does 2D).