GoKawiilTo AirPlay content from your iPhone or iPad to a TV, first confirm that both the TV and the iPhone are connected to the same Wi-Fi network, and make sure that AirPlay is turned on for your TV. To check, go to the TV's Settings menu and look under Network, Connections and Apple AirPlay & HomeKit, then enable it if it isn't already. (The menu options might be slightly different depending on the brand of TV.)
Once confirmed, open the content from a compatible app on your iOS device, like Prime Video or Disney+, and select the AirPlay icon at the top right. It will look like a tiny rectangle with an upward-facing arrow. For services like YouTube, tap the cast symbol (a rectangle with Wi-Fi wave lines) and select AirPlay from there. Then, choose what device you want to link if more than one pops up.
For AirPlaying images from Photos, press the Share button first (the square with the upward-facing arrow), then choose AirPlay from that menu. This may be the sequence with some other apps, too. For music, you'll find the AirPlay icon (an upward-facing arrow with three arcs above it) within the music playback square on Control Center.
It's worth noting that if you plan to AirPlay frequently to a specific TV, you can adjust settings so this happens automatically, as long as your iPhone or iPad has the latest OS. Go to Settings, select General and then AirPlay & Continuity. Under Automatically AirPlay, you have three choices: Never (follow the manual steps noted above every time), Ask (the device will suggest when it thinks you might want to AirPlay and wait for your confirmation) or Automatic (your device will initiate an AirPlay connection without any action from you).