Let the test you want the results of run, and the results will be in the upper right corner though it takes awhile to stabilize. It has a test for everything. There are a few to test 4k capability.
Also, the 4k banner should appear when it plays 4k content and only the highest priced plan has it though currently there aren’t many shows in 4k.
Also be sure to enable HDR on your TV. I know I’m watching 4k when it switches to the HDR mode on my LG.
