CustomMainMenu

Install the mod in the launcher, launch the game.

Press the keyboard shortcut: Ctrl + P + M

Open minecraft folder > open config folder > open mainmenu.json file

{
    "images":
    {
        "title":
        {
            "image" : "custommainmenu:textures/gui/minecraft.png",
            "posX" : -137,
            "posY" : 30,
            "width" : 512,
            "height" : 512,
            "alignment" : "top_center"
        }
    },
    
    "buttons":
    {

        "multiplayer": {
          "text": "selectServer.select",
          "posX": -100,
          "posY": 72,
          "width": 200,
          "height": 20,
          "action": {
            "type": "connectToServer",
            "ip": "{server-IP}"
          }
        },
        
            
        "options":
        {
            "text" : "menu.options",
            "posX" : -100,
            "posY" : 132,
            "width" : 98,
            "height" : 20,
            "action" : 
            {
                "type" : "openGui",
                "gui" : "options"
            }
        },
        
        "quit":
        {
            "text" : "menu.quit",
            "posX" : 2,
            "posY" : 132,
            "width" : 98,
            "height" : 20,
            "action" : 
            {
                "type" : "quit"
            }
        },

      "language": {
        "text": "",
        "posX": -124,
        "posY": 132,
        "width": 20,
        "height": 20,
        "action": {
          "type": "openGui",
          "gui": "languages"
        }

        ///If you want to make a different interface, uncomment these lines for convenience
      }//,
        //"refresh":
        //{
        //    "text" : "",
        //    "posX" : -154,
        //    "posY" : 132,
        //    "width" : 20,
        //    "height" : 20,
        //    "texture" : "custommainmenu:textures/gui/buttons.png",
        //    "action" : 
        //    {
        //        "type" : "refresh"
        //    }
        //}
    },
    
    "texts":
    {
        "mojang":
        {
            "text" : "Copyright Mojang AB. Do not distribute!",
            "posX" : -197,
            "posY" : -10,
            "color" : -1,
            "alignment" : "bottom_right"
        }
    },
    
    "other":
    {
        "splash-text":
        {
            "posX" : 90,
            "posY" : 70,
            "color" : -256,
            "alignment" : "top_center",
            "texts" : "file:minecraft:texts/splashes.txt"
        },
        
        "panorama":
        {
            "images" : "minecraft:textures/gui/title/background/panorama_%c.png",
            "animate" : true,
            "animationSpeed" : 1,
            "blur" : true,
            "gradient" : true
        }
    }
}

Replace {SERVER-IP} to your MineCraft server IP with port

Paste this text into the file.

Next, open your game server on the launcher server and go to the configs folder

Create a config folder and create a CustomMainMenu folder in this folder

Move the mainmenu.json to this folder. Restart the launcher server and the launcher