Viral RNA will have multiple genes that code for different things. I’m the case of coronaviruses, the RNA will have a gene that codes for a polymerase that makes copies of the whole rna genome and have genes that code for the proteins necessary to make a virus particle.

In the case of retroviruses, they don’t have a code to copy their own RNA that leaves the infecting virus particle but instead they convert their RNA genomes into DNA and integrate into the cellular DNA at which time they use the cell’s own machinery to make RNA.