Some mobile service providers do not like it if subscribers use their phone hotspot to bring internet connectivity to their TV for streaming lots of data. So contact your carrier to see what is possible, what limits apply for hotspot use, and if extra costs might be applied if you exceed said (monthly) limits. You’ll find that unlimited plans are not really that unlimited …
Technically, the iPhone is capable of bringing internet to other devices through the hotspot feature. Then the phone becomes the Wi-Fi access point for other devices.
How to set up a Personal Hotspot on your iPhone or iPad - Apple Support
If Personal Hotspot is not working on your iPhone or iPad - Apple Support