You can either set the timezone at database level, or at session level (… or directly when accessing a date-like datatype, using the
at time zone construct).
From the documentation:
The TimeZone configuration parameter can be set in the file
postgresql.conf, or in any of the other standard ways described in Chapter 19. There are also some special ways to set it:
The SQL command
SET TIME ZONEsets the time zone for the session. This is an alternative spelling of
SET TIMEZONE TOwith a more SQL-spec-compatible syntax.
PGTZenvironment variable is used by libpq clients to send a
SET TIME ZONEcommand to the server upon connection.