The BTR3K itself doesn't have eq capability. Eq would have to be applied externally by the player app or phone's audio system.
Not entirely true.
When your use LDAC on BTR3K, then the onboard EQ is disabled as the DSP function on the Bluetooth SoC inside BTR3K doesn't have enough processing power to both decode and EQ LDAC at the same time. But if you use any other Bluetooth codec besides LDAC (*selectable in the app), the onboard EQ function can be activated via app on BTR3K and it will apply to all sound streaming to BTR3K, regardless on whether it is music, games, youtube, etc. It will also remain active after restart until it is disabled via app. So only when you are using LDAC, then you need to use external EQ system either on your smartphone or player app.