Android 10: How can I switch to external loudspeakers during a call (the screen is black and locked and nothing happens if I plug the loudspeakers)?

I have a Motorola "moto e" phone running Android 10. Unlike in the case of my old Windows Phone when, during a call, it was enough to plug the 3.5 mm jack with 3 contacts of my external loudspeakers into that phone and the sound switched immediately to the loudspeakers, in the situation of this "moto e" the loudspeakers receive no sound if their jack is plugged during a call. I guess that, while talking with somebody, when the screen is black and locked, I can activate somehow the screen of the "moto e" and, by setting something, direct the sound to the external wired loudspeakers or to a Bluetooth wireless speaker. **How can I reactivate the screen and do the above mentioned settings?** (In most cases, the screen of the phone has to go black and be disabled by the proximity sensors because in 80% of the time I use the phone with its internal speaker.) Incoming call screens.