For something that would seem to be of keen interest to a lot of people, the top Google results combining the word “landing page” with “WordPress” have a lot of noise. You get a bunch of best theme lists (e.g.), 95% of which are variations on a generic image with a CTA button scrolling down to 3-4 icons denoting competencies and you get the idea. I guess this is because these themes are themselves “landing pages” of a sort? You also get Book Landing Page, which looks fabulous and is impossible to use.
Anyway, if you take the next most desperate expedient of Googling something like “how do I make a landing page in WordPress,” you get a bunch of tutorials for “page builder” plugins like Elementor and Beaver Builder, which seem great until you see them slither quietly around the fact that you have to pay for these things to use the features in the tutorial.
In their free incarnations at least, Elementor and Beaver Builder work within the confines of an existing theme — so if you’ve got a header, footer, sidebar, &c, this isn’t going to add up to a good landing page. However, it’s not hard to build an asymmetric two-column layout with an image, text, and a button that looks pretty much just like Book Landing Page; it’s just in the confines of the theme. So if you blank out the rest of the page, you can make something pretty nice.
This, I found rather too late at night, can be achieved with the Blank Slate plugin. So if you don’t mind (or, like me, would prefer) doing the design of the page yourself, Blank Slate and Elementor will get you a landing page that looks however you want without the need to FTP into your WordPress install and modify code, or even the need to change your theme.