Dism.exe /online /Cleanup-Image /StartComponentCleanup /ResetBase

This is a command that can be used to remove all superseded versions of every component in the component store in Windows 10 or later.

Technically, that gives typically 1Gb free disk space back.

For fixing Calendar entries still missing / Search returning 0 results in Outlook Search, despite search index being rebuilt and Outlook data selected as pool of data for search source, go with a pass of deinstalling/reboot/reinstallating the feature.

That is :

DISM /online /disable-feature /featurename:SearchEngine-Client-Package

reboot

DISM /online /enable-feature /featurename:SearchEngine-Client-Package

reboot

After the restart, go to the control panel / Indexing options / advanced / Rebuild / OK
When the Indexing is completed, close Indexing Options window and open Outlook, test searching.

Boot from a Windows 10 Install Media (USB disk)

Select Next on language/region

Select Repair PC option on bottom left

Select Troubleshoot

Boot a command prompt

run diskpart

list disk to identify the internal hard disk

select disk # to select the proper disk

list the disk volumes – list vol

Identify the EFI hidden volume # number (Hidden, kind of 512Mb, could be formatted FAT32)

Selection this EFI hidden volume : select vol #

Assign a drive letter : assign letter=n:

exit

browse from command line to this EFI drive letter N:

Repair the BCD boot : bcdboot C:\windows /s n: /f UEFI

Repair the MBR : bootrec /fixmbr

Reboot the machine