In the WordPress Dashboard, go to Appearance > Themes and browse the WordPress theme library. You can filter by industry, features, and design style.
On the next screen, you can search for 11,000+ free WordPress themes available in the official WordPress.org themes directory.
You can sort them by popular, latest, featured, and other feature filters (i.e. industry, layout, etc).
Many themes are free, but premium themes are available on marketplaces like Theme Forest for more customization options.