The enemies in tower defense simulator seem to turn so smoothly like a normal human would. My tower defense game has nodes which the enemies turn straight instead of smooth curve.

I tried to use Bézier Curves to smoothen each turn every corner but that only made it worse.

You could also write special code for the mob movement, instead of using the usual walk to point you could add something using CFrame.Angles() to turn the mob in the direction of the point (You could use attributes on the point)

If you are interested in just a perfect curve around corners, you can calculate positions on the circumference of the circle with the current angle (in your use case, probably iterate it from 0-90 degrees (but in radians)) and move the enemy there.

local x = cOrigin.X + RADIUS * math.cos(currentAngle_RAD)
local z = cOrigin.Z + RADIUS * math.sin(currentAngle_RAD)
part.Position = Vector3.new(x, part.Position.Y, z)