Here's how I got it to quickly switch over to the Semi Annual enterprise channel
Set the Group Policy to the Semi Annual like the instructions in say in https://learn.microsoft.com/en-us/deployoffice/updates/overview-update-channels
To force it over faster, I run these commands on workstations, which will make Office close and then reopen the applications but be in Semi Annual mode in about 10 minutes. Usually have some delay between the commands. Obviously there's a lot of ways to change the channel, these are just what I did to prevent actually having to reinstall Office, and get it to go fast. Results may vary.
#Change the settings to SemiAnnual via click to run
"C:\Program Files\Common Files\Microsoft Shared\ClickToRun\OfficeC2RClient.exe" /changesetting Channel=SemiAnnual
"C:\Program Files (x86)\Common Files\Microsoft Shared\ClickToRun\OfficeC2RClient.exe" /changesetting Channel=SemiAnnual
#Have click to run double check and 'realize' the channel changed (checks the Group Policy setting)
schtasks.exe /Run /TN "\Microsoft\Office\Office Automatic Updates 2.0"
#Try to make sure the Office Click to run actually starts updating it and will close and reopen office forcibly.
powershell.exe -C "$result = Start-Process -FilePath 'C:\Program Files\Common Files\Microsoft Shared\ClickToRun\OfficeC2RClient.exe' -ArgumentList "/update user displaylevel=false forceappshutdown=true" -PassThru -Wait;$result"
powershell.exe -C "$result = Start-Process -FilePath 'C:\Program Files {x86)\Common Files\Microsoft Shared\ClickToRun\OfficeC2RClient.exe' -ArgumentList "/update user displaylevel=false forceappshutdown=true" -PassThru -Wait;$result"
#double check version a while later after it updates
powershell.exe -C "Get-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Office\ClickToRun\Configuration' | Select-Object -ExpandProperty VersionToReport"