No. A factory reset does not change the activation date. The first power-on date is permanently recorded on Xiaomi’s servers.
If you have a Xiaomi account synced to the phone: how to check activation date of xiaomi phone top
If you want the truly accurate activation date to check your warranty or see if a reseller cheated you, use Method #1 (Mi Verification Website) or Method #2 (Xiaomi Community App). These are the only official sources. If you want the truly accurate activation date
Never trust the date on the box sticker, as boxes can be resealed. Always go to Xiaomi’s server. Now that you know how to check the activation date of your Xiaomi phone like a pro, you can buy and sell with confidence. how to check activation date of xiaomi phone top