Player Controller game

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

public class PlayerController : MonoBehaviour
{
    public const float defaultMS = 10f;
    static Timer timer1;
    public Camera camera;
    public float moveSpeed = 10f;
    public static float MS = 10f;
    public float jumpForce;
    public float raycastDistance;
    private static float time = 5f;
    private static bool speedBoostRanOut;

    public Rigidbody playerRigidBody;
    public Transform playerTransform;

    bool isCrouchPressed;
    bool isJumpPressed;

    bool isCrouching = false;
    bool isStanding = true;

    Vector3 tempScale;
    Vector3 curCamHeight;

    public Vector3 crouchCamHeight;

    void Start()
    {
        camera = Camera.main;
        curCamHeight = camera.transform.position;
    }

    void Update()
    {
        isCrouchPressed = Input.GetButtonDown("Crouch");
        isJumpPressed = Input.GetButtonDown("Jump");

        float zMovement = Input.GetAxis("Vertical") * moveSpeed;
        float xMovement = Input.GetAxis("Horizontal") * moveSpeed;

        zMovement *= Time.deltaTime;
        xMovement *= Time.deltaTime;

        playerTransform.Translate(0, 0, zMovement);
        playerTransform.Translate(xMovement, 0, 0);
    }

    void FixedUpdate()
    {
        moveSpeed = MS;
        if (isGrounded() && isJumpPressed)
        {
            playerRigidBody.AddForce(0, jumpForce, 0, ForceMode.Impulse);
        }
        if (isCrouchPressed)
        {
            if (isCrouching)
            {
                Stand();
            }
            else
            {
                Crouch();
            }
        }
    }

    public static void ActivateSpeedBoost(Collision collision)
    {
        // constant until death
        MS += 2;
        collision.collider.enabled = false;
        collision.collider.transform.position = new Vector3(1, -100, 1);
    }

    private void Stand()
    {
        MS *= 2;
        moveSpeed *= 2;
        jumpForce = (jumpForce - 3) * 2;

        tempScale = transform.localScale;
        tempScale.y *= 2f;
        transform.localScale = tempScale;

        camera.transform.position = new Vector3(camera.transform.position.x,
            camera.transform.position.y + 0.6f,
            camera.transform.position.z);


        isCrouching = false;
        isStanding = true;
    }

    private void Crouch()
    {
        MS /= 2;
        moveSpeed /= 2;
        jumpForce = (jumpForce / 2) + 3;

        tempScale = transform.localScale;
        tempScale.y /= 2f;
        transform.localScale = tempScale;

        camera.transform.position = new Vector3(camera.transform.position.x,
            camera.transform.position.y - 0.6f,
            camera.transform.position.z);

        transform.position = new Vector3(
            transform.position.x,
            transform.position.y - 0.6f,
            transform.position.z);

        isCrouching = true;
        isStanding = false;
    }

    bool isGrounded()
    {
        return Physics.Raycast(playerTransform.position,
            Vector3.down,
            raycastDistance);
    }
}