ComponentExtensionMethods.cs

using System;
using UnityEngine;

namespace Kogane
{
    public static class ComponentExtensionMethods
    {
        public static GameObject FindByNameContains<T>
        (
            this T self,
            string name,
            bool   includeInactive = false
        ) where T : Component
        {
            var children = self.GetComponentsInChildren<Transform>( includeInactive );

            for ( var i = 0; i < children.Length; i++ )
            {
                var child = children[ i ];

                if ( !child.name.Contains( name, StringComparison.Ordinal ) ) continue;

                return child.gameObject;
            }

            return null;
        }
    }
}

GameObjectExtensionMethods.cs

using System;
using UnityEngine;

namespace Kogane
{
    public static class GameObjectExtensionMethods
    {
        public static GameObject FindByNameContains
        (
            this GameObject self,
            string          name,
            bool            includeInactive = false
        )
        {
            var children = self.GetComponentsInChildren<Transform>( includeInactive );

            for ( var i = 0; i < children.Length; i++ )
            {
                var child = children[ i ];

                if ( !child.name.Contains( name, StringComparison.Ordinal ) ) continue;

                return child.gameObject;
            }

            return null;
        }
    }
}