It really depends on what you're selling. I've found course sales pages a waste of SEO to be honest, mostly because the SERP is full of ads, aggregate review articles or courses pulled from huge sites like Udemy. All of this decreases your chances of showing up with a single course sales page. However, I have also seen people have success with SEO on their course sales pages, but I wonder how much of that traffic really converts. I say, instead of stressing too much with SEO on your course sales page, leverage SEO to fill your funnel. This could be via an article that's highly related to your offer (eg "How to Become a UX Designer"), offer some type of freebie to get someone on your email list (like a free module of your course, guide etc) and nurture them towards a sale with a great email sequence. It's very hard to convert cold traffic to a high-ticket offer, so I think SEO works best in this case to pull in qualified leads to your email list where you can nurture them for a sale later.