Rewrite the site in PHP 8

There is a site on the self-written engine. The cattle code is terrible.
The site has the following functionality:

Admin panel:
Adding articles, editing, deleting.

The site itself:
Parser of branches (information is taken from another site and entered into the database)
Determination of the visitors city
Articles (blog)
Article assessment
Comments

What to do:
Rewrite to PHP 8. Save all the functionality of the site and the structure of the URL.
Leave lazy load for images, scripts, maps and metrics.