I believe the S8 does not have an IR emitter so you would need a smart TV or some other setup to do it. I have the Logitech Harmony Ultimate remote, which includes the Harmony Hub. The Harmony Hub connects to WiFi and emits the IR signals for the devices configured. I can control my TV literally from ANYWHERE I have an internet connection on my phone (Pixel 2 XL) but I usually only do it while at home.
If you have a smart TV (and use the TV for volume and channel control) your TV would need to have an app that supports that level of control. My LG TV also has that but I only use the TV for the display, the channel and volume controls are through different devices.
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