There are many really helpful SEO tools that are worth the money.
If you're asking for optimizing your website, here are my suggestions.
1. Yoast or RankMath. Both are equally great for the purpose they were made for (I personally prefer the free version of Yoast).
2. Lazy Load. The weight of your webpage decides how fast it will load. Text content on your page isn't gonna weigh almost anything, but the images are. Make sure you have a Lazy Load plugin (there are a few good ones) to optimize your images.
3. Wp-Rocket or LiteSpeed Cache. You have to take care of your website's caching optimization. These plugins are kings for this purpose.
These are the most important ones I believe. Then goes plugins for blocking comment spams, contact form abuses, CSS performance optimization, JS execution delay, and others that are good for optimizing the overall performance of your website.