Setting "Require Check Out" to Yes means that when you upload a file into the document library, it automatically becomes check out.
Even if you set "Require Check Out" to No, users also can check out a file. And if you want other users to see and edit the file, you need to check in it first.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.