By default, all IIS logs are stored on the C: drive. This is not recommended, however, because on the one hand this causes performance loss (depending on the configuration) and on the other hand there is a risk that the system drive will run full and the OS will crash.
How to move the IIS logs for individual IIS sites is described here: Moving IIS Log Files (using PowerShell)
Moving IIS Logs
Copy the following code into a text file (e. g. Notepad) and change the path in the second line. Save the file as PS1 by changing the file extension from filename.txt to filename.ps1. Run the file filename.ps1 as administrator on the server where you want to move the log files of all IIS sites.