There is all sorts of ways to keep an eye on it.
You could have a peak on Bundlephobia
Bundlephobia will give you a look at the total size — both zipped and unzipped — along with download times, the number of required sub-dependencies it has, and whether or not it can be tree-shaked (tree-shook? tree-shaken?).
Speaking of "phobia," there is also Package Phobia that shows the publish and install sizes of individual packages:
You could let VS Code tell you right in the editor
Your import and require statements can lett you know the size of that particular inclusion with the Import Cost extension.