display custom user fields with twig?
You can configure which fields are displayed in the view mode compact:

admin/config/people/accounts/display/compact


Then you can in twig display all fields with

{{ content }}


or single fields with

{{ content.field_example }}


To put a user in a page template you can use Twig Tweak:

{{ drupal_entity('user', 1, 'compact')


The third parameter is the view mode and you can use theme hook suggestions to catch this with your custom user twig to make adjustments of the user fields.