2018 Mazda 3 with 125k miles

I am buying 2 owner 2018 Mazda3 with 125k miles in it from a private party.

What should I inspect in the vehicle? I am think of taking it to mechanic before buying. Will they be able to know everything in the first inspection?

What do you think is the fair price?

Should I be prepared for major maintenance from a mazda3 with 125k miles in it?