Gmail less secure apps being locked down

It is the email program itself that does the authentication with a mail server.
When you setup your email program, it asks a couple questions and setups the email program to connect to an email server.
And you can go back in and tweak these settings.
In Outlook, it is under TOOLS>ACCOUNT-SETTINGS.
Google wants you to use OATH2 authentication.
OAUTH2 is available in some [but not all] versions of Microsoft Outlook:
PRODUCT:         OATUH2 authentication:
Outlook 2007     Not available
Outlook 2010     Not available
Outlook 2013     Yes, but disabled by default.
Outlook 2016     Yes
Outlook 2019     Yes
Outlook 365       Yes