It will depend on your music source. If you play for example “Wicked Game” by Chris Isaak from Tesla’s streaming Romance selection, you should notice the difference especially between Off and High. Much richer sound quality in bass and vocals. I can detect a difference between Standard and High during the vocals. Also if while playing this song for example and with audio volume set to near mid volume level, put your fingers on the upper A pillar speaker and toggle between the Standard and High settings with the other hand. You should be able to feel the difference in vibration between the two settings. Standard is definitely softer vibration as the volume increases.
I wonder if SR+s have immersive sound Always On in Standard setting to differentiate it from the Full Premium package which has the additional High setting. Try holding your fingers on the upper A pillar speaker on “Wicked Game” vocals and adjust your speaker volume upwards while fingers are there and see if you can feel any vibration, if so those speakers are being used. You guys have got me curious as to the difference between Immersive sound on the partial and full premium packages.
The Full Premium package’s audio has 14 speakers, 1 subwoofer and 2amps power. Not sure what SR+ has installed. Pretty sure immersive sound is delivered by just the upper A pillar speakers for the driver/passenger enjoyment. That upper speaker is missing on the SR car which has no immersive sound.