Nginx on Debian and Ubuntu makes use of logrotate to keep access logs small. Logs are rotated daily, and everything that's older than 2 days gets gzip-compressed. To create a total report of all accesses to a nginx webserver, follow this tutorial.
This should work with Debian and Ubuntu:
apt install goaccess
This example creates a GDPR compliant report that ignores crawlers and outputs everything into one report.html file. We don't resolve hostnames and do not query GeoIP databases. Depending on the number of accesses recorded, this may still take hours.
cd /var/log/nginx zcat -f access.log* | goaccess --log-format=COMBINED --anonymize-ip --ignore-crawlers --real-os - -o report.html
The status will show how many log lines have already been processed. To get an idea about how long this would probably take in total, you can count the existing loglines in a second terminal. This will go real quick:
cd /var/log/nginx zcat -f access.log* | wc -l
To view report.html, you can either move it into a reachable html directory or download it to your PC and open it directly in your browser.