You can get free pampers by signing up for pampers coupons and offers at
https://www.pampers.com/en-us/coupons-offers
You can also get free pampers or other brands of diapers through churches, food banks looking on Facebook marketplace, Craigslist etc.
Some parents will have leftover diapers that they want to give away to someone in need and you can sometimes find those free diapers through Craigslist or Facebook marketplace.
I've seen some free baby and toddler diapers and even free adult diapers on Craigslist and Facebook Marketplace.
If you can't afford Pampers you can try some other cheaper brands of diapers such as Luvs diapers or even Gentle Steps diapers from Dollar General.
I used to use Pampers on my kids but started using Gentle Steps diapers from Dollar General on my kids and find that they are even more absorbent than Pampers.
Pampers with the new 3 channel system makes them less absorbent and so they don't absorb as much pee as they used too.
The Gentle Steps diapers don't have those absorb channels and absorb very good.
I even have a 8 year old son that wears the Gentle Steps size 7 diapers for bed wetting and he wets a lot and they absorb very good and don't leak.
He also wears them when on long road trips in case he has to pee and can't find a toilet.