You can switch to any testnet using the below option if the chain supports both mainnet and testnet.
Switch to chain specific view from the “switch chain” modal and select your desired network like Cosmos Hub, MANTRA and others.
If you’re using “All chains” view, networks option won’t come under hamburger menu.
Click on the Hamburger menu.
Now go to network under the preferences tab.
Select the Testnet and you can now experience the Testnet network.