I’m not exactly sure what you mean by “tab of the website”. I checked the site and I didn’t find any search bar as well to point me to this “tab”. Here’s what I see on my end – [redacted by request of user.]
Can you provide a screenshot of the part you wish to change?
You don’t need a plugin to change your page name, but as Elvin said if you want to customize it, yoast SEO and rankmath are the two most popular SEO plugins, you can give them a try.