If you are using a custom DTH I’ve had success turning it into a light by either adding a light capability to the code, or specifying an OFC device type, like this
definition (name: "GE 46203 Dimmer Switch", namespace: "mwav3", author: "Tim Grimley", ocfDeviceType: "oic.d.light")
Or even more advanced would require a custom capability/presentation.
However, if using a stock DTH, or the device appears from a direct integration (ie a Kasa outlet from Kasa integration), I’m not aware of any way to change it to a light. It’s a pretty big limitation of this new app how difficult it is for users, or even developers for that matter, to change the look of devices in the app.