There’s lots of competing information regarding the effect pagination has on SEO.
Some claim paginating long pages and posts helps SEO. Others suggest including all content on a single page is the way to go. PLP accommodates both approaches, via the single page option and Ajax, which means users can use the approach that best matches their SEO goals and metrics.
The most important aspect of SEO-friendly pagination seems to be the presence of a canonical URL and giving bots the ability to crawl all page/post text at once.
WP natively supplies the former, and PLP’s single page option takes care of the latter.
Page-Links Plus helps WordPress developers, site managers, and lay users paginate content easily & efficiently.