If you're wanting to buy some thick disposable adult diapers you can check out Northshore Supreme adult diapers.
Those are pretty thick for a plain white adult disposable diaper and I wear them myself when I just want a plain white adult diaper.
The Northshore supreme diapers work great for long road trips as well and can hold up really good to several wettings.
Also check out Rearz barnyard diapers or Abuniverse Super Dry Kids diapers which are a pampers replica of the old plastic backed pampers diapers like I wore myself when I was a toddler.
Abuniverse has a lot of adult diapers that are thick and very absorbent and Abuniverse also has a plain white adult disposable diaper that is thick as well.
Check out there website
https://abuniverse.com