Hello Riccardo Scagnoli,
You can easily hide the featured image on all post globally. Have a look here on documentation. After that go to post and edit that post and scroll to down and you will get the options to enable the featured image for that specific page only. After doing this, images will hide on all post and only that post will enable where you enabled the featured image.
To hide featured image globally:
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From Customize, go to Single Post Options > Feature Image Option.
Checked on Hide Featured Image to hide the featured image on single post.
You can easily override the featured image on individual page from Single Page/Post.
and to enable on individual page. Look here on documentation.
Regards,
Acme Supports