Changing your Minecraft version can let you choose which version to join the Hypixel server with! You can change your version to anything after 1.8.9, as the Hypixel server will still support 1.8.9 and higher.
To change your Minecraft version, head back to your launcher. You can click the up arrow next to the green Play button to bring it back to the latest released version of Minecraft.
You can also change your version to an older one by going to Launcher Options. Clicking "Add New" will bring up a new configuration which lets you use a different version of Minecraft.
You can name it and change the version in this menu. If it says "release", then it is an official version of Minecraft. If it says "snapshot", then it is a testing version of Minecraft. Snapshots may not be able to connect to the Hypixel Server, we advise you use official releases only.
Hit save and go back to the News tab. You now have a new version of Minecraft that you can play on!