As all features to be implemented inside Horizons tool, you would need to directly prompt and request the SEO settings to be implemented by the application and the tool itself will give you any needed steps from your side.
Note that it's better to avoid requesting more than 5 actions inside message if you prefer to write in the chatbox of Horizons. Also, be aware that Horizons tool generated results work better when prompting using AI generated text (like Gemini or ChatGPT).
When it comes to setting up some SEO features inside your Horizons project:
Regarding update meta title and meta descriptions, such prompt works: update meta title 'my web app'
Regarding adding a favicon - you are unable to upload image for now, but it's added to our team plans
Regarding a WWW prefix: you can add it your web application by going to your domain's DNS settings and adding the following CNAME record to it:
Type: CNAME
Name: www
Point to: yourdomain.com (insert your domain without https:// or www)
TTL: 300
You can check the final result in the example below:
After you do this, all is done and you only have to wait! Have in mind that such DNS changes might take around 24 hours to fully propagate in all servers and be visible in all devices.
Regarding your web application indexing and display inside search engines, please follow the steps here.
Feel free to reach our support if you have any additional questions about SEO