Technical SEO is an area of SEO that covers optimizations that improve search engine ranking by making your site easier for search engines to crawl. For example, it could be improving site load time and making redirects work properly.
Essentially, it’s the process of ensuring your website can be seen, crawled, and ranked by search engines.
This is where technical SEO comes in, as it can help you improve the technical characteristics of your website to improve organic traffic.
It doesn't matter how old your site is. You can use this technical seo checklist https://collaborator.pro/tools/checklist-for-seo to make your site better and better.