You can increase the download speed for installing packages using DNF by updating the maximum number of simultaneous package downloads.

Start by editing the /etc/dnf/dnf.conf file:

$ sudo nano /etc/dnf/dnf.conf

Add the following line to enable DNF parallel downloads:

max_parallel_downloads=10

Another option is to select the fastest mirror from the Fedora public mirrors by adding the following line:

fastestmirror=True