I bought an audi

Just got my first audi its a 2014 S5 SC its at 120k miles right now no rattle on start and it was cali kept its in utah now. When i drove it home from dealer i got a check engine light and a warning that said coolant system fault turn off engine// anyways i topped off the coolant with 50/50 peak violet cuz after it had cooled down the coolant level was low. Anyways i had it for almost a day and its back at the dealer now while they look at it. I understand if its been sitting on the lot a while too plus 120000 doesnt exactly help but i know they can be reliable with maintenance so if anyone wants to help by sending a guide to follow or what milestones to start switching out older things.