I have an iMac Retina 4K 21.5 inch from 2015 on os Monterey 12.7.6. I see that iMac Retina 4K 21.5 inch 2019 can still get Sequoia, but does the fact that my machine is from 2015 leave me out of luck to update to Sequoia? If I can't update to Sequoia, is there another later OS I could get? I have my Mac set for automatic updates, but I don't know if this is working, or if I've just gone as far as I can go with this Mac.