If statements in update

Hi, I just started to learn programming and I have so many questions. I understand that making to many if statements in update is kind of a no no. So if I want to listen after key presses I could just do many if statements in update like this:

 void Update () 
     {            
         if (Input.GetKeyDown ("space"))
         {
             call this funktion1();
         }
         if (Input.GetMouseButtonDown (0))
         {
             call this funktion2();
         }
         if (Input.GetMouseButtonDown (1))
         {
             call this funktion3();
         }
 and so on.......
 }

How do I do this in an acceptable manner? Would it be better to do:

 void Update () 
 {            
     if (Input.anyKeyDown)
     {
         StopCoroutine("CheckButtonDown");
         StartCoroutine("CheckButtonDown");
     }
 }
 
 IEnumerator CheckButtonDown()
 {
 
     if (Input.GetKeyDown ("space")) 
     {
         call this funktion1();
         yield return null;
     }
         
     if (Input.GetMouseButtonDown (0))
     {
         call this funktion2();
         yield return null;
     }
         
     if (Input.GetMouseButtonDown (1))
     {
         call this funktion3();
         yield return null;
     }
 

Is this better? Or even worse?

Or where do I put the if statement to check if I should move the camera, eg if its near the edge of the screen. If I want to be able to move it while Time.timeScale = 0 Eg:

 void update()
 {
         if(Input.mousePosition.x <= 0) 
         transform.position -= transform.right * constant;
 
         if(Input.mousePosition.x >= Screen.width) 
         transform.position += transform.right * constant;
                     
         if (Input.mousePosition.y <= 0) 
         transform.position -= transform.forward * constant;
                     
         if(Input.mousePosition.y >= Screen.height) 
         transform.position += transform.forward * constant;
 }