After turning on "Visible to other devices", it can be scanned and recognized by other devices. You can turn off this feature when you don't want your bluetooth device to be discovered by other devices.
Setting path:
*realme UI 5.0 & above versions remove this switch. When pairing other devices for the first time, the phone can only be searched by other devices within two minutes of turning on the Bluetooth switch or being on the Settings > Bluetooth page state.
realme UI 4.0 & 3.0: Settings > Bluetooth > three dots in the upper right corner > Advanced/More settings > Turn on Visible to other devices
realme UI 2.0: Settings > Bluetooth > Advanced settings > Turn on Visible to other devices
realme UI 1.0: Settings > Bluetooth > two dots in the upper right corner > Advanced settings > Turn on Visible to other devices
realme UI R & S & T & Go & U: not support
Related Articles:
How to connect to a Bluetooth device
Unable to search for Bluetooth devices