how i can get fossil pokemon with perfect IVs?

fossils are bought in konikoni city but does soft resetting i get a fossil pokemon with perfect IVs?

I would guess that's one way to go about with it.

Another way is to just breed said fossil Pokemon with a 6 IV Ditto and try to get perfect IVs that way. I'd argue it's far less of a time-consuming task than soft-resetting.

Breeding would be the fastest way. And soft resetting for a perfect 6IV pokemon would take a TON of time. It would be okay if youre soft resetting for Nature. Theres a ton of breeding guides online. Try searching for one.