So I have a Google account signed into Chrome through which I keep bookmarks, etc. However, I use a different (work) account for most of my calendar needs. How can I make it so that when I go to calendar.google.com, it defaults to an account other than the one associated with the Chrome app itself?
What a default account is
In many cases, your default account is the one you signed in with first. On mobile devices, your default account can vary depending on your device's operating system and the apps you use.
To change the default account, sign out of all your Google accounts then first sign-in by using the account that you want to use as default. For details see the above link.