If you want to create a wallet offline (in this case Trust wallet)
Trust wallet does not let you use it in a properly airgapped manner, since you cannot import or export unsigned/signed transactions. You can keep it offline while you generate a wallet, but then you would need to go online to be able to broadcast that transaction, and so it isn't airgapped. Further, given that Trust wallet is closed source and owned by Binance, it remains a terrible choice for even a hot wallet.
OP, if you want the security of an airgapped wallet, then the first thing you need to do is get yourself a device which you can make permanently airgapped. This means that it will
never connect to the internet again, not even momentarily. Ideally this should be an old laptop or computer, but you can also achieve this (although not as well) with an old phone. Once you've done that, you format the device and install a clean OS on it, set up your offline wallet on this airgapped device, and then use your device with an internet connection only to monitor your addresses and create transactions which your offline device will then sign for you.