When i run a search in Google for my website site:sitename, only a few posts are showing up with the post title. most of them are showing as Page 1 of 10 – Site Name.
How to make the post titles displayed in the search results instead of pages.
In the Google Search Console the posts are indexed properly.
GP has no control over how SERPs are displayed. You would need to use an SEO plugin to affect that behaviour. Before doing so read this article in regards to Archive Pagination displaying in SERPS: