@sellandb I can look into why that isnt working. In the meantime, there are a few things you can do to achieve your desired result.
As @aziz mentioned above, content is prioritized by list order in Builder.io: Visual Development Platform. If you move Homepage - New User above Homepage in the list, then your original query should give you desired result:
https://cdn.builder.io/api/v2/content/page?apiKey=d8a6546473bd4f2794811a138f34b99a&userAttributes.urlPath=/&userAttributes.newuser=true&limit=1&fields=id,name,data.newuser
Similarly, if for some reason you don’t want to change the stack order, you can explicitly set the original Homepage to target for newuser=false, I think that should limit which page you see. However I wouldn’t recommend it since it is always best to have a fall back page without any limiting parameters.
As for setUserAttributes, you should be able to just include i
builder.setUserAttributes({
urlPath: '/',
newuser: true
})
inside whichever component you are integrating to Builder. You can see an example in the SDK documentation here
Not sure your exact tech stack and setup, but if you are setting the newuser attribute based on say a cookie, you may need to run whatever logic for setting the user attributes within the browser, and you can see examples of how to do that here: