I bought the standard roku streaming stick back in 2018 that supports 1080p only supposedly. I just got a new tv and when I go into the roku to display type it has the automatic at 4k hdr10 at 60fps selected. Does this mean it’s actually displaying at 4k or is it capped at 1080p and just says 4k display?
What's the model number displayed under Settings->System->About?
Settings > System > About will show you your Roku model number. Streaming Stick models 3810 and higher support 4K.