Another URL is generated with endings like: “/ page / 02

Those URLs are from archive pages of some sort. If the URL of your lead includes page/2/ or whatever number, the user is not on an individual post page, they are on the second (third, fourth, whatever) page of an archive listing. It’s possible to stop pagination by specifying -1 posts per page in settings, but if you have a lot of posts, the resulting archive lists will be extremely long. And you will not gain any more insight into what the visitor was looking at. You are better off with page/2/ IMO. Then the posts they could be viewing is limited to 10 or so posts.

It’s not normal for URLs which contain /page/2/ etc. to correspond to any single post. Lengthy posts can be paginated, but in that case the URL would not have /page/, but just the post slug and number, as in /hello-world/2/. URLs with /page/ normally only correspond to archive lists, such as those related to a taxonomy term, such as /category/uncategorized/page/2/. What you describe does not sound normal. It must have been introduced by your theme or a plugin.

For the leads to exist, there must be links to such pages somewhere on your site. Are you able to determine where these links appear? We need to look at how these links are generated to figure out a way to prevent it. Do these links lead to actual content or is the result just a nothing found message?

I see. WP should normally 301 redirect from the erroneous paged link back to the base URL. There are two separate issues then. Why does the redirect not happen and where do such links come from in the first place? Solving the latter would render the former moot.

Look through your access logs for such paged requests to see what the referring page is. The referring source should be corrected so such links are not generated. The requests I just made of course do not provide useful referrers.