can i know if a sent email has been read?

No. Scammers have used invisible pixels in emails in the past that will report to their server when an email is opened, so they can continue to send you more emails, but Apple has essentially blocked that ability with its Mail protections to prevent an email from "phoning home" to report the users activity.

I would consider that an invasion of my privacy if another user was able to monitor my activity while using my computer, unless I wanted them to know.

Ask the recipient to respond to you that they read the email.