Sennding secure email?

If I want to send an email with attachment (usually in Word, Excel or
Powerpoint) so that it is secure, and so that the attachment can only be
opened by someone who knows the "password" that we agree upon, is there a way
to do this?

I wasn't familiar with an available option in Outlook, or any specific
programs or coding that allow for this.

Btw, can emails themselves be password protected so that the intended
recipient has to enter an agreed upon password, just to read the content of
the email (as well as access any attached files included)? If this is
possible, than I wouldn't need to secure and password protect the attached
file if the recipient can't even access the content of the email itself
without a password.

Any suggestions would be greatly appreciated!

Dan