There are 56,000+ plugins available at the WordPress.org repository. That's plenty to choose from when you need more functions for your website.
So which plugins do I recommend?
Only install plugins you really need
I recommend only installing plugins that you really need. Badly coded plugins can slow a website down, allow access to hackers, or even break a website.
The best recommendation I can give you is to search at https://wordpress.org/plugins/ for the features you need. Check that the plugin is compatible with the latest version of WordPress and that it's been updated within the last few months. And that there's many thousands active installs. Reviews will give you a picture of what users think about the plugin. And the support forum will give you an insight as to what problems other users have encountered and whether the developers fix things that have been reported.
And always use a test website to try out plugins and themes before you risk installing them on your live website. And, as MKearns mentioned below, create a backup before you make any major changes to your website.