Hi,

To open a specific user form you need to define the id of the user which you need to open,

user = self.env['res.users'].search([], limit=1)

#Here you want to mention the ID of the form view you want to open

form_view_id = self.env.ref('your_module_name.view_id_of_your_form_view').id

return {

    'type': 'ir.actions.act_window',

    'name': 'User Form',

    'res_model': 'res.users',

    'res_id': user.id,

    'view_mode': 'form',

    'view_id': form_view_id,  # Specify the ID of the form view

    'target': 'current',

    'context': {'no_breadcrumbs': True},

}

Hope it helps