Quite often, I make big long winded posts on my blog that take up the whole page.
Is there any way to set it so that I can just have the title and the first few sentences of the post shown, and readers can then select “read more”, or something to that effect, to view the rest of the post?
There are ‘excerpt’ designed for the problem you are facing. It’ll only show you a summory of your entire post. However, I’m not sure if every theme uses excerpts. One that I know of that does, is the Hemingway theme.