I’ve never done the actual implementation myself, honestly. Redirects can be done via .htaccess (or equivalent), server side, or JavaScript.
Theoretically, yes, it’s that easy. However, pages should have 1:1 redirects for each page URL that matters. Then a strategy to prune the ones no longer needed/outdated by allowing them to 404, redirect to the most relevant subfolder, or just send to the main domain should be considered.
The list can be quite long. There’s more to it than all this as well, but that’s the general gist.