2 inch cut in pool liner.

How old is the liner?

If the liner is in otherwise good shape, a patch should be fine. Liners as they age get weaker and weaker. So if this cut was due to something specific, go for it. If a mysterious reason, and the liner is old, you may get more in other places starting to show up soon - then replace the liner. The life span of patches varies a lot, but I have gotten several years out of some. Enough to stretch things to the point where I really did need to replace the whole liner. But if the patch starts to leak sooner than expected, it is really hard to patch a patch - so then new liner time.
 
I would try the patch, it can't hurt. Something I have had good success with is the Gorilla waterproof tape. I used it on an old plastic ladder and it stayed good for a few years until we got rid of it. It stayed underwater fine for the repair I used it for; took the ladder out of the water at end of season and then back in the start of season and it didn't come loose.

I would use a pool patch then use the Gorilla tape over that. Or use 1 patch over the tear then another patch over the patch. Either way overlap the top layer to keep the bottom layer sealed.
 
Best to go with 2 patches. One larger than the spot then one larger than the first.
Round the edges on the patches so it doesn’t curl.
The glue in the kit at lowes is ok (its been holding for me 🤞)
but the boxer glue is the best.