Confused about matching resonants

I am currently in study for my Tech License. I know I need to match my transceiver and feed line to a 1:1 swr reading. I understand that, just hook up the swr meter between the transceiver and coax cable and take a reading. But isn’t it true that even having a 1:1 swr match between radio and coax I could still have a mismatch between feed line and antenna, say 5:1? So how do I match the feed line to the antenna? A balun? And how do I know I have a mismatch to begin with? I think an antenna tuner would make the radio to feed line happy but would it really eliminate the imbalance between the feed line and antenna? I plan to use standard hf coax, an antenna tuner and a vertical antenna. Thanks for any input. 73’s Dave.