Hi,

is_created only visible for the admin user
Add the groups parameter for the field

is_created is_created = fields.Date(groups="base.group_system")

phone only the admin can update it

First we need to create a boolean field and assign default values for that field based on the user's group.

is_created_test = fields.Boolean(default=lambda self: self._default_is_created_test(), store=True)

def _default_is_created_test(self):
 if self.env.user.has_group('base.group_system'):
    return True
 else:
     return False

add that field in xml

<field name="is_created_test"/>

then set the attributes like this

<field name="phone" attrs="{'readonly': [('is_created_test', '!=', True)]}"/>

Regards