How do I add the timezone field to a profile?
This is not supported by CiviCRM but you can do a small change in your existing CiviCRM file as shown below and clear civicrm cache, the profile form should then should allow you to add timezone field of address.

diff --git a/CRM/Core/DAO/Address.php b/CRM/Core/DAO/Address.php
index b1e00a83dc..ee9bf2d945 100644
--- a/CRM/Core/DAO/Address.php
+++ b/CRM/Core/DAO/Address.php
@@ -731,6 +731,7 @@ class CRM_Core_DAO_Address extends CRM_Core_DAO {
           'table_name' =&gt; 'civicrm_address',
           'entity' =&gt; 'Address',
           'bao' =&gt; 'CRM_Core_BAO_Address',
+          'import' =&gt; TRUE,
           'localizable' =&gt; 0,
           'html' =&gt; [
             'type' =&gt; 'Text',