Setting up a Network through Chainlist.org

Go to chainlist.org, select a network (in this example we'll choose Polygon Mainnet) and click "Connect Wallet" and "Connect" in the pop-up wallet window.

Then click "Add to Trust Wallet" and confirm the addition of the network. Switch the network if necessary.

If the network is not pre-installed in the wallet, when you click "Add to Trust Wallet" you need to confirm the addition of the network.