There is not one penetration enhancing ingredient which works for everything nor is there something which would reduce penetration of everything (except wrapping yourself in cling film before applying a product LoL). Regarding cling film and occlusive agents: they’re maybe the best and oldest ‘penetration technology’. They generally increase penetration of most everything if they don’t result in for example a broken emulsion with the actives floating on top.
I’m taking the other example of @Adamnfineman
: Mineral oil does reduce menthol penetration by the same ‘penetration mechanism’ it enhances penetration of salicylic acid: Solubility (or insolubility, respectively). If an active ingredient is more soluble in the base than the skin, it reduces penetration (unless the base is readily penetrating skin such as DMSO) but if the active is a lot less soluble in the base than the skin it enhances penetration.
A minimum solubility in the base and the skin are more or less required for either effect.
And then there are the other penetration enhancing effects too… many of which are only poorly understood and more theory and guesswork than proven facts. I wouldn’t go as far as saying that penetration enhancers are well known. Some are, true, but most are just abused by marketing and it would only be okay to call them penetration enhancers when the final product in question has actually been shown to do so. Anyway, if you know those effects, then you also know what might be done to revers/weaken them. As a rule of thumbs (guesswork quote > 90% 😉 ) I would say that formulating something (especially emulsions) wherein one doesn’t explicitly plan for enhanced penetration of a given ingredient more likely ends up with a product which hampers its penetration than one which accidentally enhances it.