How can I automatically flag new comments?
Flag ID should be the ID of the flag being set. If you go to /admin/structure/flags, and Edit the flag, the machine name/ID of the flag will be at the end of the URL -- so /admin/structure/flags/manage/{flag_id}.
I've not used Rules on D8, but for Entity ID, if you click &quot;switch to data selection&quot; and then click the field, I think it should give you some autocomplete options to help select the data you want. You'll likely end up with something like &quot;comment:id&quot;.