Do we need a 'livery' tag?
I don't know.
It seems unlikely that this tag will be very useful.
I'll list some questions where it might or might not apply. There may be a few more out there. I think there might be one more on identifying specific Saturn I or V launches based on some differences in markings, but I may be mis-remembering.
Are there roughly similar ones already?
- I found a few but not all using the space-art tag.
- We don't have a "markings" or "symbol" or "logo" tag
- Per comments we do already have insignia, color and design with which some items below might better be tagged instead.
Note, I don't know how many of these describe markings that would count as "livery".
- Why are Soyuz rockets painted with different colors? "Progress rockets I saw have different "liveries", multicolored like this"
- What is the purpose of the black-and-white patterns on some rockets?
- Did the Saturn V rocket have any purely aesthetic features that didn't serve an actual function?
- Was there a rocket launched to space with Japanese manga characters painted on it?
- What do these markings on SpaceX's ship Mr. Steven represent? (it's a
boatship, not a spacecraft) - What organizations correspond to the logos on this ORBITEC Vortex engine rocket?
- Humanoid silhouette on SpaceX's Starhopper; what does it represent?
- Why does Curiosity have two images of itself on itself, or is one a QR-code?
- Saturn V Small Rectangles On S-II Stage
- Did Wernher von Braun really have the "Saturn V painted as the V2"?
- Livery on rockets? (also mentioned in the question)