Two factor authentication is your friend.
Something you have.
Something you know.
Your face, your fingerprint, your retina, etc.
A simple passcode that’s in your memory.
Search warrant won’t help them.
But maybe Apple Corp. would.
I have an iPhone 8 plus with Touch ID. You can disable Touch ID for unlocking the phone, but leave it enabled for apps that use it. That provides two factor authentication for those apps (somewhat).