How will I use IsTouching function

Questions & Answers
1

Unity explains it but I just don’t know how to implement it.
I made a script that lets me pick up the object.The code is going to be in a cube.I just want to be able to pick the object that has this script by holding f button.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class pickup : MonoBehaviour
{
   
    bool Isholding=false;
    Vector3 Distance;
    public GameObject player;
    public GameObject collidersGameobject;
      
        void Update()
        {
            if(Input.GetKeyDown(KeyCode.F)&&   is touching  collidersGameobject=true                 )
            {
                Isholding=true;
                Distance=transform.position-collidersGameobject.transform.position;
            }

            if(Input.GetKeyUp(KeyCode.F))
            {
                Isholding=false;
            }
            if(Isholding=true)
            {
                transform.position=collidersGameobject.transform.position+Distance;
            }
        }

        
}
2

There is no equivalent version of the isTouching function for 3D collision. i suggest using OnTriggerEnter or just detect the distance bewteen the player and the cube and if youre within for example 20f between the cube and the player and you press F the cube will be pick up. in this case make sure the cube has a rigidbody on it. this is an old script of mine that i combined with yours, i havent tested this specifc code but it should work.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;

 public class pickup : MonoBehaviour
{

float throwForce = 400;
Vector3 objectPos;
float distance;

public GameObject cube;
public GameObject playerHand; /// the position you want the cube to be held at
public bool isHolding = false;

void FixedUpdate()
{
    distance = Vector3.Distance(item.transform.position, tempParent.transform.position);

    if (distance>= 20f)
    {
        isHolding = false;
    }

    if (isHolding == true)
    {
        cube.GetComponent<Rigidbody>().velocity = Vector3.zero;
        cube.GetComponent<Rigidbody>().angularVelocity = Vector3.zero;
        cube.transform.SetParent(playerHand.transform);

        if(Input.GetKeyUp(KeyCode.G)) // this will drop and throw cube - optional
        {
            cube.GetComponent<Rigidbody>().AddForce(playerHand.transform.forward * throwForce);
            isHolding = false;
           
        }
    }
    else
    {
        objectPos = cube.transform.position;
        cube.transform.SetParent(null);
        cube.GetComponent<Rigidbody>().useGravity = true;
        cube.transform.position = objectPos;
    }

    if(Input.GetKeyUp(KeyCode.F) && (distance <= 20f))
    {
        isHolding = true;
        cube.GetComponent<Rigidbody>().useGravity = false;
        cube.GetComponent<Rigidbody>().detectCollisions = true;
    }
}
3

Thank you,I am going to create a sphere collider instead of istouching,and then I am going to check if that
object is touching.