Light trailing effect.

[Gujjuguy]

Instrument: M21

How can we get light trailing effect in background with face closeup?

[Sidhabhi]

You have to use pro mode and adjust iso and shutter speed(if your device supports pro mode)

[Gujjuguy]

In pro mode shutter speed is not available. Only ISO and WB is available.

[Anikroyale]

You cannot as your phone doesn't support advanced pro mode.

[Sokul]

If you install custom rom, then there is a plethora of options available (since your device doesn't support Knox, it doesn't matter either way. You can always roll back to stock). Search in Telegram about Galaxy M21