StreetForum/Assets/Resources/Scripts/UI_Stuff/UIContentFitter.cs

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

public class UIContentFitter : MonoBehaviour
{

    // Start is called before the first frame update
    void Start()
    {
        Fit();
    }

    // Update is called once per frame
    void Update()
    {

    }

    public void Fit()
    {
        HorizontalLayoutGroup hg = GetComponent<HorizontalLayoutGroup>();
        int childCount = transform.childCount - 1;
        float childWidth = transform.GetChild(0).GetComponent<RectTransform>().rect.width;
        float width = hg.spacing * childCount +
                      childCount * childWidth +
                      hg.padding.left +
                      childWidth;

        Vector2 size = GetComponent<RectTransform>().sizeDelta;
        GetComponent<RectTransform>().sizeDelta = new Vector2(width, size.y);
    }
}