What effect is created by extending a sentence into the next line or stanza?

A stanza is a group of lines within a poem. Like lines, there is no set length to a stanza; however, there are names to stanzas of certain length. If you have two line stanzas, they are called couplets. And if you extend another sentence to it making 3 stanzas, they are now called the targets. Four lines stanzas are called quatrains and so on. So, this will be the effect created by extending a sentence into the next line or stanza. Poets fit the sentences to show unity in its visual and aural effect.