Want to watch the American League Championship Series in the best possible quality? You'll need to stream it. Fox Sports is keeping up its recent habits by streaming 2019 ALCS games in 4K HDR through its namesake app and Fox Now. The same caveats still apply. You'll need a 4K-capable Roku device or an Apple TV 4K to watch. And this is technically an upconverted 1080p signal rather than true 4K -- you might not see every dirt smudge on player's uniforms. This could nonetheless be the best view you get, and you can tune into the non-HDR 4K feed using FuboTV and conventional broadcasters.
There will be other technical marvels if 4K HDR doesn't pass muster, although some of this will have to wait until the World Series. You can watch 4D Replays (really, adjustable 3D) of World Series batter swings and home base attempts, follow the path of balls in 3D through Pitchcast and see whole-stadium views through FlyCam. And yes, Fox is dabbling with 8K. It's partnering with Sony to take an 8K camera to "select" World Series games to both record them at ultra-high resolution and use the sheer number of pixels to zoom in on key scenes. You likely won't be watching live games at full quality on an 8K TV, but the technology to make it happen is rapidly approaching.