If you’re talking about actually scaling, like a CAD drawing, then no.
If you’re talking most of the appearance and function, then yes! There is a scale model of a Browning M2 machine gun (which normally fires 50 cal ammo) that fires 22lr instead. It will set you back about $20,000.
There is a whole youtube rabbit hole you can go down showing videos of miniature versions of larger (larger caliber) guns. The smallest I saw was “replica” Civil War Navy revolver that the whole gun was about 6cm long. It was a functional gun that had a powder charge with a projectile.