You seem to be talking about a severe body odor problem that is outside of the norm. In which case, it is probably a good thing to consult a dermatologist to see if it has any particular cause, and if so, act on that in the proper way. Diet can sometimes help (meat and protein tend to increase odor, and garlic is of course a no no), but only so much.
I'm not sure covering with perfume could solve the problem. I assume you've tried antiperspirants. That said, certain marine scents are so powerful that they cover bad odors well. I actually don't like those scents, but cover they do. An example is Light Blue. Alternatively, you could try some old powerhouses; perfumes in the 70s and 80s were designed with smokers in mind, so somehow they tend to work well with other odors. Stuff like Aramis, Azzaro pour homme, Antaeus, Rive Gauche for man, and the like.
That lavender is calming is a tenet of aromatherapy, but I don't think there's any evidence. But lavender does smell fresh and clean, though it is usually not very long lasting.