Ring of Giant Mingling

Ring, rare (requires attunement by a giant or humanoid)

While wearing this ring, your size changes to match the size of those around you. If you are a Large creature and start your turn within 100 feet of four or more Medium creatures, this ring makes you Medium. Similarly, if you are a Medium creature and start your turn within 100 feet of four or more Large creatures, this ring makes you Large. These effects work like the effects of the enlarge/reduce spell, except they persist as long as you wear the ring and satisfy the conditions.