Recently I helped someone who had bought a new 2021 Mazda. The clock
was not set at the dealer and like most cars these days, the settings
are buried in the infotainment system menus.
Steps
Use the infotainment controller on the center console to go to Settings
Push the controller to the right to switch 'tabs' until you get
to Clock
Pick your timezone from the 'Time Zone Select' list.
If the clock is still off by an hour, go down to 'Daylight
Savings Time' and click the controller down
Notes
This should work with a Mazda CX-30, CX-5, CX-3, CX-5, or other Mazdas from 2020
or 2021.