How to list files of a Debian package without install

dpkg -c (or --contents) lists the contents of a .deb package file (It is a front-end to dpkg-deb.)

dpkg -c package_file.deb

To work directly with package names rather than package files, you can use apt-file. (You may need to install the apt-file package first.)

sudo apt-file update        
apt-file list package_name

As stated in the first comment, apt-file lists contents for packages in your already-configured Apt repositories. It is irrelevant whether any particular package is or is not installed.

Use --contents instead of -L:

dpkg --contents PACKAGENAME

When used in this manner, dpkg acts as a front-end to dpkg-deb, so use man dpkg-deb to see all the options.

You can also use an archive browser to view the package contents.

dpkg --contents will let you look at the uninstalled package. If the .deb is not on your system yet, do

apt-get --download-only install pkgname

The package will get downloaded to /var/cache/apt/archives but not installed.