Try adjusting your map layers using the Map > Map Layers menu
Turning on the coastline helps with coastal borders, and if you are located anywhere but USA using the data layers helps with general bolding (Doesn't work for USA because the data layers overlap the map you want to look at)
Thanks Tushar, I will try to explore the Mapbox then.
Thanks Peter. I am trying to create a global map. I tried the coastal line but the effect is not that great. After all, the coastal lines are not the country borders.