It’s possible, but I think it’s typically used for ingress (ie same IP, but multiple destinations, follow BGP to closest one).

I don’t think I’ve seen a similar case for anycast egress. Naively, doesn’t seem like it would work well because a lot of the internet (eg non-anycast geographic load balancing) relies on unique sources, and Cloudflare definitely break out their other anycast addresses (eg they don’t send outbound DNS requests from 1.1.1.1).