Going the other direction.
WHY PEOPLE DO IT
The owner cannot edit the static site They need a shop, booking or membership They want to publish without a developer
HOW TO APPROACH IT
Set up WordPress Recreate the design as a theme Move the content Preserve every URL Redirect anything that changed
THE CONTENT STEP
For a small site, recreating pages by hand is fastest.
For a large one, converting content files to an import format.
WHAT TO PRESERVE
URLs, above all Page titles and meta descriptions Images
WHAT YOU GAIN
Editing by anyone Plugins for functionality
WHAT YOU TAKE ON
Updates Security Backups Performance work
WHAT TO SET UP IMMEDIATELY
Caching Backups A real cron job Security basics
THE HONEST TRADE
Ease of editing, in exchange for maintenance.
For most businesses that trade is worth it.