Hi @gregy68980908, did you consider to pass the value using GET parameter. Sling model has access to request, so you should be able to retrieve GET param value and update data exposed by model respectively, e.g assuming this is url you are using now
/content/we-retail/language-masters/en.model.json
it can be changed to something like that (this is request you will sent from React)
/content/we-retail/language-masters/en.model.json?attribute=value
In your sling model you can access value like this:
@Self
private SlingHttpServletRequest request;
private String attributeValue;
@PostConstruct
protected void init() {
this.attributeValue = request.getParameter("attribute");
}