Often, but not always. The dependency depends on the type of smart glasses and the feature you are trying to use.
Products such as Ray-Ban Meta commonly rely on a companion phone app for setup, settings, media management and connected AI features. The glasses can still perform some on-device tasks after setup, but the phone remains part of the overall system.
XREAL-style display glasses do not necessarily need a phone specifically. They need a compatible video source—such as a phone, laptop or handheld gaming PC—with supported video output. Some models are powered by that source device.
Some glasses include more on-device processing and can run selected features without keeping a phone active every moment. That does not mean every feature works offline or without initial app setup.
Instead of “Does it need a phone?”, ask: “Which features still work when the phone is disconnected?” That gives a much more useful answer.
Rokid documents offline translation that can run without Wi-Fi or cellular data after pairing, activation and downloading the language model in the app. XREAL One-series glasses, by contrast, are external displays that require a compatible video source and power connection.