By default, the work profile is isolated from the personal profile. Applications, data, and accounts in one profile cannot access those in the other. This is the foundational privacy and security guarantee of the work profile model.
However, administrators can selectively relax this boundary using cross-profile policies. The level of control depends on whether the device is personally-owned (BYOD) or company-owned (COPE).
What can be configured
BYOD vs COPE differences
On personally-owned work profiles, the default cross-profile restrictions are more permissive toward the user - for example, sharing from personal to work is allowed by default. On company-owned (COPE) devices, administrators have broader control and can lock down both directions.
Best practices
For more on work profile architecture, see What is an Android work profile?.