How to create a perfect bound A4 magazine?

https://indesignsecrets.com/indesign-secrets-video-laying-book-cover.php

This show how to do this .

Wehn you make your magazine remove the pages for the cover and send that to the printers.

Send the cover spearately

You will also require 2 additional pages as your magazine needs to be in multiple of 4's.

It needs to be 64 pages or 68 pages - regardless - 66 pages will leave blanks.

Will your magazine be printed by a commercial printer, or were you planning to do this on a network printer/copier? If it's being done by a commercial printer, you should start talking to them now (if you haven't done so already). They can tell you what they need. They might want you to make the front and back covers as separate pages, and the spine as a third, for them to assemble. They might also ask you to make one document the width of both covers and the spine, but either way, they will need to tell you what size the spine needs to be. That will be based on the type of paper chosen (different stocks will be of different thicknesses).

Also, ask them about the page count. Most books are done with page counts that are divisible by 4 for production reasons. If your 66-pg book needs two pages added to complete a signature, you would be the best person to decide whether you want additional content on those pages, or if you would prefer blank pages, you can decide where they go. But that might not be an issue, so asking early is better than finding out at the end.

When you create a new file check the Facing Pages Options.

Later you can change it in File > Document Set up …