Yes, you can use a ring light with a smartphone. Many ring lights come with a universal phone holder that can securely hold your smartphone in place while you use the ring light for photography, video calls, or live streaming.
To use a ring light with your smartphone, simply attach the phone holder to the ring light stand and adjust the holder to fit your phone. Then, position the ring light and phone in a way that provides the desired lighting and angle for your photos or videos.