Regarding 3rd party clients, you can do that on desktop, thanks to Proton Mail Bridge: https://proton.me/mail/bridge
On mobile, we cannot do that due to how our encryption works.
Regarding the case you shared, the name/address of the terrorism suspect was actually given to police by Apple, not Proton. The suspect added their real-life Apple email as an optional recovery address in Proton Mail. Proton can't decrypt data, but in terror cases Swiss courts can obtain recovery email.