You can sideload it but if your device doesn't contain the required DRM to play 4k for
netflix, it won't. For example
xiaomi phones can't play HD netflix content because they don't have the required DRM certification. You can however use an external device which is able to play 4k netflix(
nvidia shield,
intel 7thgen+, gtx 10 series, firestick, etc) if your
TV is HDCP 2.2 complaint.