Detecting Overlapping when placing items

Hello everybody! I am making a sorting system where items are spawning on a conveyer belt and then placed in the box. My problem is that I need to showcase the item placement inside that box. What I need to achieve is 1) check if items intersect/overlap when placed in the box 2) if they fit in the free space, place them. I've managed to get a result using GetComponent().bounds.Intersect but it's not exactly what I am looking for - I need items to be close together. Is there an easy way to check if two cubes overlap inside the scene and, if not, to place them next to each other (or on top of)?