If the sticker on the door jamb does not give the build date or the maximum gross weight of the vehicle then it may be that this sticker is placed elsewhere on the vehicle. Failing this you could contact Kia directly and ask them to provide you with the build date from the VIN.

In respect of the SOS button, you are correct in that legislation came into force in 2018 that all new cars should have an SOS button, but an important distinction is that the term 'new cars' refers to newly-launched models. We have seen reports that other vehicle owners have raised this issue with dealers and the DVSA, and have been told that because their vehicle is not a new design produced after the 2018 deadline it is not legally required to have one. Your generation of Sportage was introduced in 2016, so this may be the reason it is not fitted with an SOS button.