Hi! The following code is an example how to use fields_view_get:

@api.model
def fields_view_get(self, view_id=None, view_type=False, toolbar=False, submenu=False):
    context = self._context or {}
    res = super(Partner, self).fields_view_get(view_id=view_id, view_type=view_type, toolbar=toolbar, submenu=False)
    if not self.env.user.has_group('base.user_root'):
        doc = etree.XML(res['arch'])
        # The field you want to modify the attribute
        node = doc.xpath("//field[@name='email']")[0]
        node.set('readonly', '1')
        setup_modifiers(node, res['fields']['email'])
        res['arch'] = etree.tostring(doc)
        return res
    return res