I don't know where you all come up with this option "Widgets" option. Do you really have Garmin fenix 5 Plus? In all threads they mention the Music app being default option for Hot key on Down button. I found a solution that works, really simple, described in this thread: forums.garmin.com/.../see-your-regular-watch-face-during-activity-is-possible
Okay so there are basically 2 ways how to make this work:
1) System - Hot Keys - assign Widgets (it is really useful to switch to English and find out the name in your languge based on the items above and below, this was my problem) to the button / buttons you wish.
2) Activity settings - Disable LAP button function in the activity you do and the LAP button will take you to the same place - you lose LAP, but you save one Hot key slot.
I've actually disabled the normal Lap button and added Lap as a hotkey to the long press of the Lap button. I find it safer because it prevents extra laps from accidental presses of the Lap button. And it provides easy access to the watch face by short press.