How to mirror iPhone to smart TV?

To use the screen mirroring feature, your TV must support AirPlay. You can check if your TV model is compatible by visiting this list: Home app - Accessories - Apple

If your TV doesn't support AirPlay, you can still mirror your screen using a cable. Here's a helpful guide: Connect iPhone to a display with a cable – Apple Support (UK)

For a wireless alternative, consider downloading mirroring apps from the App Store, such as DoCast, TV Mirror, or Screen Mirroring App. These apps are reliable and let you stream photos and videos as well as mirror your screen to smart TV.

Is the smart TV AirPlay-compatible? If so, then check its manual and/or menus to find out how to enable its AirPlay function.

If it does not support AirPlay, you will need the help of an AirPlay-compatible set-top box (like an Apple TV 4K) or an AirPlay-compatible streaming stick (like some of the Roku sticks). (And a spare HDMI input on the TV.)

depend on the tv really, if it does not support airplay 2

then you can't use airplay mirror

if it support chromecast then there are some chromecast apps in app store you can use

otherwise you need an appletv box Apple TV 4K - Apple

or a cable Lightning Digital AV Adapter - Lightning to HDMI - Apple

mind you some apps and sites block airplay mirror as it can disable their DRM encryption

You pull up the control menu by swiping up at the home menu, then you select the button next to the “lock rotation” button. Finally, assuming you have a smart TV/Roku, you select your IPhone to screen mirror to the device.

please note that i use a IPhone SE

and that not all Rokus and TVs support this feature