Although cruise ships are continuously renovated by the onboard crew, the capital projects are completed by shipyards and owner's contractors during the special survey dry-dockings, which are required by Flag/Class, every 5-yrs (newer ships), or 2 drydocks every 5 yrs (older ships).
The Viking Star completed her first special survey drydocking in Genoa in December 2019, just prior to the COVID shutdown, when they completed some hotel projects, although most of the work was mechanical, painting and regulatory. Prior to the World Cruise, I recall her spending a few days at Grand Bahamas Shipyard, where they did some additional hotel work for the World Cruise.
Not aware of any of the Viking ships drydocking during the COVID shutdown, so any refurbishment was completed by onboard crew, or owner's contractors.
The Orion's Planetarium was installed during the newbuild and a Planetarium also installed on the next ship Jupiter. It was not included on Venus.