My understanding is that with APFS, volumes exist inside containers, and the volumes all grow as much as needed, as long as there is space in the container.
But I want to limit the space for the volumes. I have a 2TB disk with two volumes – one for Time Machine and one for general storage. I don't want the Time Machine volume to take the entire physical disk. Sadly, there is no way (in macOS 11 Big Sur) to delete Time Machine snapshots, so I need to limit its space by limiting the size of the volume.