Good news — the Samsung Galaxy S20 Ultra supports eSIM, so you can install a data plan without a physical SIM card.
Go to Settings → Network & internet → SIMs → Add eSIM. If this option is available, your device supports eSIM.
Some carrier and region variants of this device may not support eSIM, including versions sold with a physical dual-SIM tray in certain markets. Always confirm on the device itself using the steps above.
