Question

Can balanced forces have any effect on a body?

Answer 1

Balanced forces can only cause a change in the shape of a body.
For example, consider a spring as shown. If we pull the spring at its two ends it gets elongated. And if we push it from both the ends, it gets compressed.
In both the cases, the net force acting on the spring is zero but the balanced forces are still producing a change in shape of the spring.