You can install Minecraft Forge for free from the Forge website, and then use it to download and enable mods.

Mojang has recently released the 1.21.9 update for Minecraft Java Edition. This new Copper Age update has brought in many major changes and features to the game, making players have a whole new ...

Then, select “Open With” and “Java”. if you don’t have Java or the Java file doesn’t work, you will need to download Java 21. This is required for Minecraft 1.21.4 mods like OptiFine.