TextMesh.fontSize

Description

The font size to use (for dynamic fonts).

If this is set to a non-zero value, the font size specified in the font importer is overriden with a custom size. This is only supported for fonts set to use dynamic font rendering. Other fonts will always use the default font size.

GetComponent.<TextMesh>().fontSize = 12;

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    void Example() {
        GetComponent<TextMesh>().fontSize = 12;
    }
}