Can I use an eSIM on a locked phone?

No. A carrier-locked phone will only accept eSIM profiles from the carrier it is locked to. You need to unlock the device first, which your carrier can usually do free once the contract is paid off.

Does my phone support eSIM?

Q: Does my phone support eSIM?

iPhone XS, XR and later, Google Pixel 3 and later, and most Samsung Galaxy phones from the S20 generation support eSIM. The quickest check is to search your phone settings for "eSIM", if the option to add one exists, it is supported. Carrier-locked phones and mainland China models are the main exceptions.

Almost certainly yes if it's an iPhone XS or newer, a Pixel 3 or newer, or a Samsung Galaxy from the S20 generation onward, and it isn't carrier-locked. That last condition catches more people than the hardware one.

The fastest way to check without reading any list: open your phone's settings and search for "eSIM". On iPhone that's Settings → Mobile Data → Add eSIM. On Android it's Settings → Network → SIMs. If the option is there, your phone supports it.

By manufacturer

Make	Supported from	Detail
Apple iPhone	iPhone XS, XS Max and XR (2018)	Every iPhone since supports eSIM. US models from iPhone 14 onward are eSIM-only with no physical tray at all. Exception: iPhones bought in mainland China ship with dual physical SIM trays instead of eSIM.
Google Pixel	Pixel 3 (2018)	Every Pixel from the 3 onward supports eSIM. Exception: Some very early carrier-specific variants were restricted to Google Fi.
Samsung Galaxy S	Galaxy S20 (2020)	S20 through the current S-series, plus Note 20. Exception: Models sold in mainland China, and some carrier-locked variants, omit eSIM.
Samsung foldables	Galaxy Z Fold and Z Flip	The whole Fold and Flip line supports eSIM.
Samsung Galaxy A	Varies by model and region	Many mid-range A-series models support eSIM, but it is inconsistent between regions. Exception: Check your exact model number rather than assuming.

The two things that catch people out

Carrier locking. A locked handset only accepts profiles from the carrier it's locked to, no matter how new it is. Your carrier can usually unlock it free once the contract is paid off, do this before you travel, not at the airport.
Where the phone was bought. Mainland China variants of both iPhone and Samsung generally ship without eSIM hardware support. The model number, not the brand, decides it.

If your phone doesn't support it

A physical local SIM bought on arrival is still the cheapest option in most countries, and a portable wifi hotspot works for a group. Neither is worse than roaming at your carrier's daily rate.