At the moment, the only "stable" SEO extension compatible with phpBB 3.2.X is the following: https://www.inveostore.com/phpbb-seo-extension-40
but it is at paid. It's not as efficient as the one on the Olympus series (dcz), but it works.
All CMS (Joomla, Wordpress, Drupal, etc.) and Forum Software (Vbuletin, SMF, etc.) have at least SEO extensions, with URLs rewritten. We must resign ourselves to the fact that the URLs rewritten on phpBB are not considered necessary, even if many users want them. Patience. It seems to me a dogmatic formulation to say that "they do not serve" and that's it. They do not serve, ok. But one can want them anyway!
Attention, the mentioned paid extension, necessarily requires either the Zend Guard Loader library for PHP (64 bit) or ionCube Loader (64 bit). One of the two. Otherwise, it does not work. The php 7 is fine. Furthermore, it costs a little more after logging in.