Can TL1-3 add <link rel=canonical href=“ to a post

hi
ive search and can see canonical gets a lot of mentions

i didnt see anything along the lines of how someone making a post can add a need for the served post to include <link rel=canonical href=“

is the served thread sufficiently distinct and a single html <body> that duplication of some content isn`t likely detected?

i guess one way around this if they just post a “…and [see this webpage](url…”
but
is there anyway currently - ?

Thnx & sorry if i put this in wrong place, asked a dup Qn etc