Is there a way we can connect /blog similar to a reverse proxy as an external service?

If I good understand your problem / question this could be done by using an External HTTPS Proxy. Everything is described in this documentation with examples.

But based on this topic by default

You need to have an ingress gateway and expose the internal service. The services within the mesh is discovered by Pilot and you can't visit internal mesh services without configure the Ingress Gateway. They're simply isolated by the sidecar rules.

There are also many similar questions on the internet. Look at the similar topics:

• Is it possible to use Istio as a reverse proxy? (similar to nginx proxy_pass)
• Istio as a Proxy for External Services
• Nginx reverse proxy with istio ingress
• Using istio as an reverse proxy for external TLS services
• How to proxy pass for another website (reverse proxy) in istio like we do in nginx https://docs.nginx.com/nginx/admin-guide/web-server/reverse-proxy/