How to create 1 new parameter in WordPress settings?

Question

WordPress

Hey!
The page has a regular html price list with more than 1000 positions.
In order not to change prices for everyone, we decided to create 1 point in the WordPress settings = % price increase.

How it is possible to organize input and saving of 1 field for number? To then display it on the page. Then I will multiply everything by javascript.

I thought to use advanced custom fields, but it seems to appear on all editing pages in general, which will be a heap

. I also thought I could somehow create 1 field in the settings, but I don’t know how.

Answer 1

https://developer.wordpress.org/plugins/settings/