How to scale an object to a certain size over a certain period of time(in seconds lets say)

Using Time.deltaTime as part of the "time" (namely, "t") argument in Linear Interpolation is almost always a terrible idea, and I never understand why it's done so frequently. Essentially, it removes the "Linear" element and makes it state/luck-dependent on exactly how it plays out without being able to reach its goal.

If you want an "animated" Lerp() function to play out, well, linearly, you'll want a fixed start and end point, with a "t" value that ranges from 0-1 over a given length of time.

 // T$$anonymous$$s example is based around multiplication for more efficient math
 private float fScaleTime;
 public float scaleTime
 {
     get
     {
         if(fScaleTime == 0f)
         {
             return 0f;
         }
         else
         {
             return 1.0f / fScaleTime;
         }
     }
     set
     {
         if(value == 0f)
         {
             fScaleTime = 0f;
         }
         else
         {
             fScaleTime = 1.0f / value;
         }
     }
 }
 
 // An editor-facing initial value, since the property would be $$anonymous$$dden in the Inspector
 [SerializeField]
 private float initialScaleTime = 5.0f;

 public Vector3 startingScale = Vector3.one * 0.1f;
 public Vector3 endingScale = Vector3.one * 5.0f;
 
 private float lerpT = 0f;
 
 void Start()
 {
     // Set the property to the Inspector value
     scaleTime = initialScaleTime;
     // Redundant in Start() in t$$anonymous$$s case, but included for general context
     lerpT = 0f;
 }
 
 void Update()
 {
     // Simple example, no conditions involved for t$$anonymous$$s
     transform.localScale = Vector3.Lerp(startingScale, endingScale, lerpT * fScaleTime);
     lerpT += Time.deltaTime;
 }

^{Edit: Fixed an obvious typo}

Thanks @Eno-Khaon, that really helped me out.