How to minimize the risks of attacks and site hacking?

Question

Information Security

There is a very sad picture, a WP site that has not been updated for 1.5 years (plugins are also not updated, they have custom code not in templates). It was decided to rewrite everything on the site and slightly change the layout. During the development of a new site, this site is in a very big vulnerability. How to minimize all risks?
Access to it cannot be closed, it should work until mid-spring 2022.

Answer 1

Make a backup of the site and place it so that it cannot be reached (before the backup).
Scan for vulnerabilities - there are a lot of WP site scanners on the
Internet Check logs for suspicious activity often

Answer 2

https://qna.habr.com/q/933705#answer_1870361
You can also change the URL of the authorization page, the plugin is "WPS Hide Login"