Here's how to check the population of New World's servers and how to find a complete server list.
Since its release New World has been struggling with cumbersome loading times and overpopulated servers. Patch 1.0.1 attempted to alleviate some of these issues by doubling their number of playable servers and increasing the capacity of new and old servers. There was an improvement in queue times and there were fewer issues with servers being filled, but with New World growing in popularity so quickly it was impossible to make everything perfect.
How to Check New World Servers' Population and Server List
Amazon Games maintains a full list of servers in every region as well as their status. Each region has their own tab with a list of all the servers playable for that region. Next to each server name is a icon indicating whether the server is online, offline, currently under maintenance or at maximum capacity. If a server is at maximum capacity a new character cannot be created in that server.
Unfortunately Amazon's server list does not include accurate data concerning the number of players in each server. For that sort of information the best source seems to be the New World Status website. This website gives people access to an incredible amount of information concerning a servers player cap, number of current players, and even the number of players queued for a specific world.