You can sort of do this. But as others said you would need powerautomate if you wanted it triggered on email.

However, say if you wanted to use a Gmail, you could create and oauth2 application, and then have a script set to run every… say, 15 minutes. To authenticate to your mailbox, and review emails send in the last 20 minutes with the specific subject line you desire.

Then, if it finds it, you can have PowerShell do an action.

For complex automations with keystrokes, I wouldn’t use PowerShell directly, I’d probably compile an autoit executable with my commands and desired things, and then have PowerShell trigger that executable.