Would coke make you appear less intoxicated?

Dealing with someone who is a functioning alcoholic; starts drinking in the morning, continues all day. Not always at an absurd pace but definitely steady. On average probably has around 15-20 “standard” drinks a day, maybe more. The other day said person sounded like they were intoxicated around mid-day. A little while later (maybe 1-2 hours) they did not seem as drunk as before. Wondering if it’s possible that they are using something else to help them “sober up”. My thought is once you are “drunk” (meaning slurring words, etc.) you wouldn’t really sober up if you continued drinking, even if at a slower pace… So I’m wondering if there may be more going on than what I previously thought. Any thoughts/insights/experiences are appreciated!