whatsapp_web/models/res_config_settings.py

from odoo import models, fields

class ResConfigSettings(models.TransientModel):
    _inherit = 'res.config.settings'

    module_whatsapp_web = fields.Boolean("Activar WhatsApp Marketing")
    whatsapp_endpoint = fields.Char(string="URL de envío de WhatsApp", config_parameter="whatsapp_web.whatsapp_endpoint")

    def set_values(self):
        super(ResConfigSettings, self).set_values()
        self.env['ir.config_parameter'].sudo().set_param('whatsapp_web.whatsapp_endpoint', self.whatsapp_endpoint)

    def get_values(self):
        res = super(ResConfigSettings, self).get_values()
        res.update(
            whatsapp_endpoint=self.env['ir.config_parameter'].sudo().get_param('whatsapp_web.whatsapp_endpoint')
        )
        return res