If you’re having a genuinely good time, there’s little in there to improve. If you’re actually happy, or actually relaxed, or anything, really, you can easily get even to overwhelming levels without using anything - assuming you have a healthy psyche and are currently in a good condition.
But then people have anxiety disorders, they may be depressed, they might have BPDs, they may have extreme burnout - and then to curb it and have a truly good time they need substances - to let go, to induce positive emotions, to relax.
Honestly this shows even with casual alcohol drinkers - remove alcohol and the party will appear bland and empty to them, they won’t be able to open up and have equally good time. They would look for alcohol in order to make the party good again. This is very problematic. And the same goes for party drugs - go ahead, hold a party with friends into drugs, but remove the substances, alcohol, etc. Not such a wonderful time, huh?
People with healthy and good mental state and no addictions can absolutely have wonderful and amazing moments with their friends without “enhancing” their feelings in any way; there is no need to enhance anything, it peaks already. If it doesn’t, look up why.