Use C# code to enable optimization settings

You can use code to enable some optimizations recommended in Optimize your Web build. If you use code to configure these settings it can save you time having to manually set each of them individually.

Note: This script only works in the Unity Editor, not in builds.

Create a C# script to optimize your Web build

To use code to enable most of these optimizations at once in your Unity project settingsA broad collection of settings which allow you to configure how Physics, Audio, Networking, Graphics, Input and many other areas of your project behave. More info
See in Glossary:

Create an Assets/Editor folder if you don’t already have one.
Create an empty C# script in the Editor folder.

Paste the following code into the script:

using UnityEditor;
using UnityEditor.Build;
using UnityEngine;

public class WebOptimizer
{
    [MenuItem("Example/Optimize")]
    public static void Optimize()
    {
        var namedBuildTarget = NamedBuildTarget.WebGL;
        var buildOptions = BuildOptions.CompressWithLz4HC;

        // Set IL2CPP code generation to Optimize Size 
        PlayerSettings.SetIl2CppCodeGeneration(namedBuildTarget,         
                                        Il2CppCodeGeneration.OptimizeSize);

        // Set the Managed Stripping Level to High
        PlayerSettings.SetManagedStrippingLevel(namedBuildTarget,     
                                            ManagedStrippingLevel.High);  

        // Strip unused mesh components           
        PlayerSettings.stripUnusedMeshComponents = true;

        // Enable data caching
        PlayerSettings.WebGL.dataCaching = true;

        // Set the compression format to Brotli
        PlayerSettings.WebGL.compressionFormat = WebGLCompressionFormat.Brotli;

        // Deactivate exceptions
        PlayerSettings.WebGL.exceptionSupport = WebGLExceptionSupport.None;

        // Deactivate debug symbols
        PlayerSettings.WebGL.debugSymbolMode = WebGLDebugSymbolMode.Off;

        //Enable WebAssembly 2023 features
        PlayerSettings.WebGL.wasm2023 = true;           

        // Set Platform Settings to optimize for disk size (LTO)
        UnityEditor.WebGL.UserBuildSettings.codeOptimization = UnityEditor.WebGL.WasmCodeOptimization.DiskSizeLTO;
    }
}

Change the script to suit your project.
From the toolbar, select Example > Optimize to run the script. Your settings update.

To change the settings for Asset Import Overrides, refer to Build profile reference.

Additional resources

Recommended Quality settings to optimize your Web build

Remove unused resources from your Web build

Unity Manual

Use C# code to enable optimization settings

Create a C# script to optimize your Web build

Additional resources