using iphone as lighting led remote

My remote controlled (wifi) hall ceiling light does not respond to the remote supplied with it anymore. The LEDs light up dimmed with the wall switches, and sometimes on full: nothing in between as hitherto.

Occasional the light will "strobe" on switching on. So, guessing that either the remote and light aren't paired, or one or the other is faulty.

How can I use my iPhone 11 to act as remote control for the light to check if the remote is at fault?