You can set the number of posts at settings > reading in your dashboard, but be careful if increasing it. There are still a large number of people out there on slower internet connection (below 1Mbps) and if a site takes too long to load, people just click away and go elsewhere.
Also, search engines use page loading times when calculating search engine ranking and if your site loads too slowly you can get penalized and end up lower in search results.
In general with just text posts (as long as they aren’t too long) I recommend keeping the number at 10 or less. If you use images in your posts regularly, I would think about 5 as a maximum. If you use multiple images in posts, I might even suggest going down to 3.
One other way to shorten posts and be able to keep more showing per page is to split the content with the “more” tag.
The “previous” or older link at the bottom of pages is automatic and will appear when the number of posts gets over the number set at settings > reading.