https://www.aclu.org/other/constitution-100-mile-border-zone
Or just a Nandroid[0][1] backup and flashing the stock rom before you go, then restoring upon return.
[0] https://www.howtogeek.com/240582/how-to-back-up-and-restore-...
[1] I don't know if this is possible with Apple phones, as I don't use them. Perhaps someone could elucidate on the viability of this option for iOS devices?