Go to Version Sync in Project A
Company-managed: Project A > Project settings > Version Sync'
Team-managed: Project A > Project Settings > Apps > Version Sync)
Click “Duplicate versions to a target project” on the top of the screen
Select Project B as target project
Note that current versions of Project A are displayed
With that configuration versions will be synced from Project A to Project B. But not from Project B to Project A.