If anyone is wondering about IE11, MS says "Internet Explorer 11 will continue receiving security updates and technical support for the lifecycle of the version of Windows on which it is installed."
Extended support for Windows 10 ends on October 14, 2025. Extended support for Windows Server 2016 ends on January 11, 2027.
Presumably one or those 2 dates could be considered the termination date for IE11. My company has chosen the 2025 date as when we will stop support for IE11 in our web pages/apps.