Hi,

If you are looking to add some constrains before saving or creating new record, you can use the constrains in odoo or override the create method and show the warning.

See how to use Constrains:

@api.constrains('model_id')
def _check_model_name(self):
    # Don't allow rules on rules records (this model).
    if any(rule.model_id.model == self._name for rule in self):
        raise ValidationError(_('Rules can not be applied on the Record Rules model.'))

Overriding Create Method:

@api.model
def create(self, values):
    if not values.get('login', False):
        action = self.env.ref('base.action_res_users')
        msg = _("You cannot create a new user from here.\n To create new user please go to configuration panel.")
        raise exceptions.RedirectWarning(msg, action.id, _('Go to the configuration panel'))

    user = super(Users, self).create(values)
    # Auto-subscribe to channels
    self.env['mail.channel'].search([('group_ids', 'in', user.groups_id.ids)])._subscribe_users()
    return user

So depending On your use case, either you can show some warning or notification if some conditions/criteria is not satisfied from the create method or from the constrains.

Thanks