You can increase your chances of spotting the planets with the unaided eye in the bright twilight arch by leveraging our visual system's creation of a negative afterimage.

Long time visual observers are familiar with this classic contrast effect or "illusion" (for more info see https://en.wikipedia.org/wiki/Afterimage):

How does this help with detecting planets or a star? The idea is to stare at a point a degree or so below the horizon, then quickly shift your gaze to where the target ought to be. The part of your retina exposed to the orange twilight now floats just above, as an aqua-teal band. The central part of your vision which was "exposed to darkness" below the horizon, is now "transparent" and well rested, ready to detect what is out of place in a short left-right scan. Farther down, you can notice the bright twilight arch but do your best to not look at it.

The effect of course fades after about 15 seconds as your eyes tire once again of looking at the bright sky. I found I could repeat the exercise every minute or two. It does help to know roughly where to concentrate your attention when you lift your gaze.

The following image is an attempt to re-create my visual impression at the time.

I stumbled upon this phenomenon at the end of a fabulous run of clear skies during the apparition of Mercury in March of 2019, when it rapidly faded evening to evening. I figured it had dropped below my threshold after a frustrating number of minutes, so I lowered my eyes down into the valley to see if I could spot any coyotes or deer by the riverside. When I lifted my gaze back up, there was Mercury decently noticeable!

After quickly recognizing what was going on, I repeated this experiment several times, then trying the reverse by deliberately staring at the brighter orange horizon then shifting up and being unable to spot Mercury.

Give it a try!