Learning by osmosis is just not a thing. You can't just smack a junior in the middle of a team that doesn't effectively do remote, but a team with a good remote culture should certainly have no issues with a junior being remote as well.
I have mixed feelings on this, it seems to me it is doable, but it requires 2 important things:
1. The Junior has worked remote before. If you get someone where this is their first remote job, unless they're incredibly organized and have a remote strategy they will lose socialization and much more.
2. A ton of work on the manager's part. Mentoring sessions, checkins, very active communication channels etc.
