Under an electron microscope the image is all gray, (like the background) no color. It is colorized later by people who are trained to recognized structures distinct from a gray background so that that average viewer can easily see them. Viruses have no color because the wavelengths of all the colors of the rainbow (visible light) are longer than the virus. So the color of a structure is chosen to stand out by the colorer. We know its size from the magnification of the electron microscope. An electron micrograph captures an image of a specially prepared specimen in a vacuum. It cannot show us a living cell, only a frozen snapshot.
The spikes on the surface of a COVID -19 coronavirus (you see in the first picture) are proteins that fit like a piece of jig-saw puzzle to receptor proteins on the surface of the host cell. This fools the cell into inviting the infectious enemy through its membrane. Once inside, the coronavirus finds a ribosome, a small organelle that makes proteins from RNA codes specific to the organism. (RNA is a single strand of nucleotides with the same sequence as the organism's DNA) . The coronavirus, which is basically RNA with a protein protective coating, is able to use the replicating machinery of a ribosome to make copies of itself. In the process, it interferes with the functioning of the lung cell to provide us with oxygen. The newly minted coronaviruses then squeeze through the cell membrane like tiny buds.
Meanwhile lots more of the virus are being replicated inside the cell. Upon re-emerging outside the cell, each virus particle is now free to infect other cells in the body and be shed from the person in tiny drops of moisture from speaking, sneezing and coughing.
Self-replication is an essential activity of all living things. Is a virus a living thing? Are there any free-living viruses? All it can do is replicate itself in the cells of a living host, which range from the smallest bacteria to us. It doesn't have metabolism, so it doesn't "eat." As long as it doesn't come across an outside environment strong enough to destroy is complicated molecular structure, it will exist (not "live") as long as it needs to exist until it encounters a receptive host.
It's amazing to see the magnitude of the infection in the microscopic world of a single sick cell.