If you're that sore, then there really is something wrong with the latching on.
Get a mirror and check underneath that the whole areola is in. If baby starts to suckle and you're not fully attached, then gently break the seal and do it again. Don't let a baby suck harder and harder if they're not positioned right.
For the first couple of weeks, it's normal to be a bit sore at the start of the feed, but it should get more comfortable after a minute or so.
Baby's suction can be incredibly strong at the start of the feed, but once they've got the nipple deep up against the roof of the mouth, the suction is just to keep it in place. If you're engorged, or if the nipple shrinks due to pain, then baby will suck hard on the tip only and that's agony.
I used to use a manual pump just before a feed to get the nipple soft and long enough. I had misshapen nipples that baby would chomp on when halfway in otherwise. Those little gums can be pretty brutal if you've not gotten the nipple in past them.
The let-down reflex timing is important too. Baby will suck hard and sometimes thrash around if the milk doesn't start flowing straight away. The expectation of pain can interfere with let-down. You then get a vicious cycle of no milk, so vigorous sucking, so no milk. Baby can get really frustrated with this and may chomp and suck harder until you're both in tears.
If this happens, then using a manual pump to get the milk flowing first, can be a solution.
Newborn babies can be really good at nursing and you think you're sorted, only to find they've 'forgotten' on day two and have to learn over again. While you do need to be patient with them, don't grin and bear it if initial soreness turns into pain. Get the latch right and the let-down sorted.