A lot of companies just suck at it too. "Here's Slack, figure it out" seems to be a common approach. In person you can pester the person next to you when you're new, overhear conversations, etc. but remote it is MUCH harder to ascertain the culture, Slack etiquette, etc (my favourite was "people write in Slack all the time, in public, even to themselves, it's your job to mute Slack when you need focus, and don't use DM's unless you really need the privacy"), but I have only seen this done very well in one place - Auth0 (pour one out :-( ) . Maybe because it started remote with founders thousands of KM apart.