Powershell Search and Delete Commands

Microsoft is retiring some of the powershell commands I use to connect and to search/delete emails from mailboxes.  I'm trying to find the replacement commands but can't seem to 'string' them together.  Can someone help me?

This is part of me connecting:

$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.of
fice365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection
WARNING: Using New-PSSession with Basic Authentication is going to be deprecated soon, checkout
https://aka.ms/exops-docs for using Exchange Online V2 Module which uses Modern Authentication.

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This is how I search and get an estimate or delete mail:

Search-Mailbox -Identity user@mycompany.com -SearchQuery 'SUBJECT:"[EXTERNAL] Subject Here" AND FROM:externalperson@externalcompany.com' -DeleteContent
WARNING: WARNING:  On July 1, 2020, the Search-Mailbox cmdlet is being retired and Microsoft Support will no longer
provide assistance.  See https://go.microsoft.com/fwlink/?linkid=2113221 to learn more.
WARNING: The Search-Mailbox cmdlet returns up to 10000 results per mailbox if a search query is specified. To return
more than 10000 results, use the New-MailboxSearch cmdlet or the In-Place eDiscovery & Hold console in the Exchange
Administration Center.

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In the above command, I will also sometimes use -EstimateResultOnly.