date_default_timezone_get
PHP 5 >= 5.1.0, PHP 7, PHP 8
date_default_timezone_get - Gets the default timezone used by all date/time functions in a script
Example #1 Getting the default timezone
Result: date_default_timezone_set: Europe/London
date.timezone: Europe/London
Example #2 Getting the abbreviation of a timezone
Result: America/Los_Angeles => America/Los_Angeles => PST