This is a list of adult websites which you could eventually use to configure DNS filters or other tipe of blocking appliances on a connection level (or do anything you want with it).
The original list comes from a Reddit post I saw some time ago.
I am not the author of this list and I do not own any kind of right on this list.
In Pi-Hole V5 you can simply add this blocklist by accessing the Admin GUI > Group Management > Adlists and pasting the link of the raw list: https://raw.githubusercontent.com/emiliodallatorre/adult-hosts-list/main/list.txt.
After you are done adding the list, you have to update gravity using either the pihole -g command from the CLI, or Admin GUI > Tools > Update Gravity.
This list is not comprehensive of all porn websites, as there are continuously new websites coming online, hence I am not responsible of children traumas if this list fails to block a porn website.
More generally, this list comes "as-is" and I cannot offer any guarantee of its completeness.