ForestElementsManager.cs

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

public class ForestElementsManager : MonoBehaviour
{

    [SerializeField] bool smallObjectsCollision = false;

    private System.Action<GameObject> disableSmallObjectCollision = (gameObj) =>
    {
        if (gameObj.name.Contains("Grass_01") || gameObj.name.Contains("Grass_02") || gameObj.name.Contains("Mushroom_01") || gameObj.name.Contains("Mushroom_02") || gameObj.name.Contains("Branch_01"))
        {
            gameObj.GetComponent<MeshCollider>().enabled = false;
        }
    };

    // Start is called before the first frame update
    void Start()
    {
        if (!smallObjectsCollision)
        {
            gameObject.ForAllChildren(disableSmallObjectCollision);
        }
    }
}