Instead of trying to show people how smart you are, which generally involves you talking and others listening, why not change it around a bit and do the smarter thing and that is learning to “listen” to others more, instead?
You will find that by listening more, you will discover just how smart OTHER PEOPLE ACTUALLY ARE.
They will freely divulge all sorts of information and some of it will be valuable.
Then if anything valuable is said, just add to your pool of knowledge thus making you smarter!
There will always be opportunities to show others how smart you are, but don’t force it. And don’t worry if you have to do more listening than talking. Wait for your moments, rather than trying to force your “moments” onto others.
For when those opportunities come, others will realise then how smart you actually are.