Many (but not all) changes to configuration files require a restart; I don't think it matters whether you are making those changes through the REST API, Manager, or editing the .conf files directly. You should check the configuration file or its reference topic in the Admin Manual to see whether a particular change requires a restart (see Restarting after configuration changes in the Admin Manual.
Thanks Chris for the response. I am sure that the configurations I am looking at need a restart(tags.conf,props.conf,transform.conf). I am just wondering as making changes through web interface needs no restart, is that the case with REST API.