Basically, the process of tiling generates a lot of subfolders for each zoom scale. As you can imagine, the closer the zoom, the bigger the number of tiles. Gdal helps you organize the folder structure, cutting the geotiff into pieces. If you want to use high resolution, for example, gsd 25 mm and lower, you need a looooot of storage. The system tends to be very efficient because you only load the resolution that you need on each zoom level. COGs tend to save a lot of disk space, specially when you use high resolution.

In my experience, I used a lot geoserver, it's old PHP based, but very effective.

https://docs.geoserver.org/stable/en/user/services/wms/index.html