Accessing Apple TV on my smart TV

The OLED65CXAUA seems to be a 2020 model TV from the CX series. Those would be supported for the Apple TV app.

List of Apple TV app-supported devices - Apple

The Apple TV app would be either pre-installed, or downloadable from the LG Content Store.

With the Apple TV app on your smart TV or third party streaming device, you can access:

• iTunes Store movies and TV shows (buy or rent);
• Apple TV+ channel featuring Apple Originals, by subscription;
• other premium Apple TV app Channels, each by subscription.

link to a payment page

I’m not sure how the procedure guides users on smart TVs during sign-up,

but this is what online support document say:

Change, add, or remove Apple ID payment methods - Apple Support

↳ on your iPhone, iPad, or iPod touch

↳ on your Mac

↳ if you don’t have an Apple device

↳ on your PC with iTunes

↳ on Android or Chromebook

↳ on the web at tv.apple.com