CentOS 7 has the "extras" repository enabled by default, but this repository typically doesn't contain many packages. The "extras" repository for CentOS primarily provides packages that are not part of the base distribution but are still considered important for some users. It may contain updates and additional packages, but it's not as extensive as the base CentOS repository.
If you're looking for additional packages or need more comprehensive software, you may need to enable and use the EPEL (Extra Packages for Enterprise Linux) repository, which is a community-driven repository that provides a wide range of additional software for CentOS.
To enable the EPEL repository on CentOS 7, you can use the following commands:
```bash
sudo yum install epel-release
```
After enabling EPEL, you can install additional packages from there. Remember to use the packages from EPEL with care, as they are not officially supported by CentOS and might receive updates and maintenance from the community.