vDos and DOXBox are free applications that lets you run old DOS Programs & DOS Games in Windows 11/10. This article shows how to use them in detail.

I have a program that runs on an individual file through the command-line in DOS. However, I was wondering if there was a way (as a BATCH file or in C++) to run this command on every file in the ...

You can hold down the Ctrl key to choose DOS from the boot menu. You can run commands in Config.sys and Autoexec.bat before Windows Me starts.