Running the Dragon orbit, it seems the spacecraft will be visible from mid-northern latitudes worldwide shortly after local sunset.
The spacecraft's trajectory takes it across the sunset termiantor (point where day turns to night on the ground below) at around 46 degees north latitude. The Earth spins under the orbit, so every 90 minutes (when the spacecraft loops back to this point in its orbit) the Earth will have rotated some hundreds of miles, and the new point at 46N experiencing sunset gets the spacecraft visible in the sky. (And the visible range will extend some distance north and south of 46N, especially south since the spacecraft is moving southeast at the time, so deeper into twilight the spacecraft is farther south.)
Takeaway is that anyone worldwide in mid-northern latitude (northern US, southern Europe, etc) may have an opportunity to see Dragon in the night sky shortly after sunset. It will only be visible for a few minutes at most, so knowing exactly when/where to look is important for spotting it. But if you want to try, it can be worth the research to get a satellite prediction sky track.
The most popular source of satellite predictions is Heavens Above, but their website seemed to be down (overload of interest?) There are other sources too. HA may come back up.
https://www.heavens-above.com/
Dragon looks like a bright star (about equal to the brightest stars) moving across the sky at about the width of the full moon every 1/2 second. Not like an airplane, no blinky strobe lights etc.
Docking with space station is in about 19 hours, so there's only about 3/4 of a day window of opportunity to see the spacecraft in free flight.