My friend asked me to make a survey on triple SIM smartphone. Can I have recommendation for it? I could really need your help on this.

For that, you will need to find a phone that has Physical Dual SIM and built in eSIM.

I can only think of Samsung Galaxy S20's or above.

Do you need all 3sim to be active?
Most phones now are 2 sim. One of the spot can be esim or card

True 3 sim are those china feature phones. I remember acer also has it