With Localisation Options open you'll be able to choose Change Timezone and select your local timezone.
From the command line, you can simply type
date and confirm the date is displayed in your desired timezone.
pi@raspberrypi:~ $ date Wed 28 Nov 11:10:33 PST 2018
The Raspberry Pi Foundation recently announced the release of Raspberry Pi OS—a new update and name change for the classic Raspberry Pi operating system Raspbian.