Can smart dimmers be used in a 3-way (multi-location) setup?

Yes, several support it. The Lutron Caseta and Diva Smart dimmers handle single-pole or 3-way configurations, and Lutron's wireless Pico companion remotes can add control points without extra wiring. Leviton Decora Smart supports wired or wire-free 3-way as well; always verify the specific model's multi-location instructions.