Does a topic sentence have to be the first sentence in a paragraph?

in the Penn foster booklet of piratical English writing process booklet 1 it says 2 different things it says it can be anywhere in a paragraph but then later on in the booklet it says its the first sentence so its hard to display answer.

Usually it is the first sentence.

But it can be the second sentence especially when the first sentence is a sentence that links to the previous paragraph.

Or it can be the last sentence.