You can browse all 46+ million certificates ever issued by Let’s Encrypt here:
https://crt.sh/?Identity=%25&iCAID=16418

The %25 in the identity URL parameter is the percent sign and used in a LIKE query so you can do things like this to find specific certs:
https://crt.sh/?Identity=microsoft.com%25&iCAID=16418

I don’t have a specific use for this yet but if you ever need to look something up this is the definitive place.