using "copy_only" makes a backup of the tlog but it does not do a truncate of the log when it completes. According to Microsoft:
opy-only log backups (full recovery model and bulk-logged recovery model only)
A copy-only log backup preserves the existing log archive point and, therefore, does not affect the sequencing of regular log backups. Copy-only log backups are typically unnecessary. Instead, you can create a new routine log backup (using WITH NORECOVERY) and use that backup together with any previous log backups that are required for the restore sequence. However, a copy-only log backup can sometimes be useful for performing an online restore. For an example of this, see Example: Online Restore of a Read-Write File (Full Recovery Model).
The transaction log is never truncated after a copy-only backup.
It does still do a backup of the tlog when running "BACKUP LOG".
The above is all just my opinion on what you should do.
As with all advice you find on a random internet forum - you shouldn't blindly follow it. Always test on a test server to see if there is negative side effects before making changes to live!
I recommend you NEVER run "random code" you found online on any system you care about UNLESS you understand and can verify the code OR you don't care if the code trashes your system.