for information: if you don’t want to use a plugin then this doc explains how to load fonts locally:
When it comes to checking what fonts are loaded, then you can simply:
a. open your site in a private / incognito browser ( it has no caching ).
b. Right Click > Inspect your site to open the Developers Tools, go to the Network Tab to see what resources are being loaded and from where.
Alternatively you can test your site here:
If you view a waterfall report it will also show a list of the network requests it makes. Just look out for any Google networks.