chromium/chrome/browser/resources/ash/settings/date_time_page/timezone_selector.html

<style include="settings-shared">
  settings-dropdown-menu {
    --md-select-width: 425px;
  }
  /* When per_user_timezone_enabled is true, dropdowns are start-aligned. */
  #userTimeZoneSelector {
    --settings-dropdown-menu-policy-order: 1;
  }
</style>
<template is="dom-if" restamp
    if="[[!prefs.cros.flags.per_user_timezone_enabled.value]]">
  <settings-dropdown-menu pref="{{prefs.cros.system.timezone}}"
      label="$i18n{timeZone}"
      menu-options="[[timeZoneList_]]"
      disabled="[[prefs.generated.resolve_timezone_by_geolocation_on_off.value ||
      shouldDisableTimeZoneGeoSelector]]">
  </settings-dropdown-menu>
</template>
<template is="dom-if" restamp
    if="[[prefs.cros.flags.per_user_timezone_enabled.value]]">
    <settings-dropdown-menu id="userTimeZoneSelector"
        pref="{{prefs.settings.timezone}}"
        label="$i18n{timeZone}"
        menu-options="[[timeZoneList_]]"
        disabled="[[shouldDisableUserTimezoneSelector_(
          prefs.generated.resolve_timezone_by_geolocation_on_off.value,
          shouldDisableTimeZoneGeoSelector)]]">
    </settings-dropdown-menu>
</template>