Create multiple basic pages with different fields I have a question to create a site in Drupal 8.

It is a website with about 60 basic pages, but each of them has different relationships, paragrphs, media.

My question is, how can I assign different fields per page and that the type of content does not grow monstrous? I am trying to reuse fields, but it has been very complicated for me.
IIUC you need the Bricks​ module. This module is similar to Paragraphs but a lot more abstract and allows for the customized options you mention. 

You will have to create all the possible "Bricks" that can be found on your pages, then it won't be difficult to create each page with the custom structure it's supposed to have. 

You don't have to use the Layout builder if your cases aren't that complex. The most important thing is to create some strategy around your different cases, analyze your needs so you know what different combinations need to be created. Go for the simplest possible solution, don't overcomplicate needlessly or you'll create a mess that is difficult to maintain.