These are steps you need to follow to enable the DApp on Trust wallet on your iPhone.

1. Start Safari Safari web browser from your iPhone.
2. Make sure to select "Trust Browser: Enable" on the URL field.
3. When you've done that after that, a pop-up window will appear on your screen that says, "Open this webpage on Trust?" Click on it to continue.
4. Return to the Trust Browser to enable your wallet.

For more read - https://www.joinarticles.com/how-do-i-enable-dapps-on-my-trust-wallet/