How do you find your phone with se model watch

Is your SE up-to-date with watchOS 17.2?

If so, press the Side Button (not the Digital Crown) once and tap the iPhone icon in the Control Center. The phone will emit a sound.

This will only work if the phone's battery still has a charge.

M1 Mac mini, macOS 14.2;  Watch, series 7 GPS/cellular, watchOS 10.2; iPad Pro 2nd Gen, iPadOS 16.7.3; iPhone 12 Pro, iOS 17.2; TV 4th Gen, tvOS 17.2; HomePods, audioOS 17.2 and Airport Express w/ Airplay 2

This side button (see picture, thanks to Dah•veed)

Use Control Center on Apple Watch - Apple Support

continue following Dah•veed’s instructions.