As Michel says, the products sold from 1/1/22 have 3 years warranty, the previous ones 2.
As long as you have the purchase invoice of the product, it will be valid for 2 years from the date of purchase.
The warranty will have to process it either with the store where the product was purchased, or directly with Samsung through its Official Technical Service, which have many authorized workshops throughout Spain.
I have a 46mm Watch 4 Classic and it is a great buy.
I hope you enjoy it, best regards!