Shades such as sage, olive, and forest green are cropping up everywhere, from TikTok remodels to glossy magazine spreads, and the move from gray to green has led to a new phrase—millennial green.

In the 2010s and early 2020s, there was one king of interior design—"millennial gray." Characterized by a monochromatic palette of gray tones, the color swept through walls, furniture, and decor ...