Do you mean with respect to balancing when endpoints come/go (e.g. a POD goes up/down)? Or something else?
In this case, it depends on the ingress controller used. The default nginx ingress case has some docs: https://kubernetes.github.io/ingress-nginx/how-it-works/
Note that nginx-ingress has limitations as a side effect of its Lua balancer vs normal nginx. As an example, it does NOT do TLS-resume on the nginx<->service hop. Normal nginx would, but the lua balancer lacks the necessary code [1]. In some high volume scenarios, this can cause trouble on the backend.
[1] https://github.com/openresty/lua-nginx-module/pull/1312
