Hello, new employees can view [Welcome Announcement] and [Sticky to Top Announcement], whether the history announcement can be viewed is depends on whether the administrator has turned on the [New Members] selection when send the announcement.

1. Desktop client DingTalk: login [Desktop client DingTalk]  -  [Work] - [Announcement] - create announcement;
2. Admin panel: enterprise admin panel (oa.dingtalk.com) - [Applications]  [Announcement]-[Create].

When the range of recipints is selecting a department, you can choose whether to allow [New Members (Visible to Department New Members)].