Chemical based sealers will often peel as the natural cedar oils degrade them, so finishing or staining cedar walls isn’t recommended. Sanding the walls with a fine sandpaper will revive the cedar scent as the aromatics dissipate over time. Another food-safe, non-toxic, and inexpensive option that I came across was coating the wood in cedar oil mixed/diluted with olive oil, which is what I went with because I happened to have those items on hand!
The pleasant odor and the deep colors of our cedar walls had started to fade after only a few weeks; the purples and reds not nearly as vibrant as they were when they were fresh. So I mixed together several drops of cedar essential oil and olive oil and applied it to our cedar walls with a piece of kitchen sponge. I really love the results — the cedar scent and color is fully revived and the deeper color adds an impressive drama to the interior of our RV bus conversion — The best part is, this job went very quickly and I have a lot of the oil left over, so whenever necessary I can quickly and easily refresh the walls again!