FPSMouseController

using UnityEngine;

public class FPSMouseController : MonoBehaviour
{
    [SerializeField] private float _horizontalSpeedMultuplayer = 1;
    [SerializeField] private float _verticalSpeedMultuplayer = 1;
    private float _horizontalAngle;
    private float _verticalAngle;
    private void LateUpdate()
    {
        var x = Input.GetAxis("Mouse X");
        var y = Input.GetAxis("Mouse Y");

        _horizontalAngle += x * _horizontalSpeedMultuplayer;

        _verticalAngle -= y * _verticalSpeedMultuplayer;

        Quaternion horizontalRotation = Quaternion.AngleAxis(_horizontalAngle, Vector3.up);
        Quaternion verticalRotation = Quaternion.AngleAxis(_verticalAngle, Vector3.right);

        transform.rotation = horizontalRotation * verticalRotation;

    }

}