First, make sure you are not using the WordPress default blog page.
In the Dashboard Settings > Reading, Make sure the front page is set to a Static page, and that Nothing is selected in the posts page drop down list (showing -select-)
In the same place, you will find the WordPress setting of max posts per Blog page which you can set t6om what you want.
Next to create your post page, you create a regular page, and in the page Attribute > Template Drop down list you select “page with posts”, and publish the page.
Once you do that, you will have ALL the Xtreme options for this page to select what posts to show and how to show them, including the number of posts per page.