
1 - New-ExchangeCertificate
2 - Import-ExchangeCertificate
3 - Enable-ExchangeCertificate
Reference:
https://docs.microsoft.com/en-us/powershell/module/exchange/new-exchangecertificate?view=exchange-ps
https://docs.microsoft.com/en-us/exchange/architecture/client-access/import-certificates?view=exchserver-2019
https://docs.microsoft.com/en-us/exchange/architecture/client-access/assign-certificates-to-services?view=exchserver-2019