Display default access privileges for relations, sequences and functions in Postgres

Using the psql(1) interactive terminal

There is another way, at least in recent Postgres versions.
Use the \ddp command

               Default access privileges
     Owner      | Schema |   Type   | Access privileges 
 role_x         |        | function | =X/role_x
 role_x         |        | sequence | 
 role_x         |        | table    | 
 role_x         |        | type     | =U/role_x

Read more about it under the Notes section here:

Using a SQL query

  nspname,         -- schema name
  defaclobjtype,   -- object type
  defaclacl        -- default access privileges
FROM pg_default_acl a JOIN pg_namespace b ON a.defaclnamespace=b.oid;

Where the value of defaclobjtype is r = relation (table, view), S = sequence, f = function.

These access privileges are only for newly created objects within the schema namespace.

If you join pg_default_act to pg_namespace you will only list default privileges that are granted using in the schema.