I currently have a working server of Nextcloud and want to take a hot or dynamic backup of it. Is there a way already present in Nextcloud or an alternative for this?
rsync for the filesystem,
mysqldump for the database, or whatever is the equivalent for your database server.
Is your server a physical machine? Or do you run your NC as a VM?
NC runs in Ubuntu, which in turn runs on the VM.
you could take snapshots or hot-backups of the hole VM. How you can do that of course depends on what hypervisor / backup tool for the hypervisor you use. Also make sure that the backup tool / hypervisor has a mechanism in place to make sure that the VM is in a consistent state before the backup procedure starts. Normally this is done by some guest agent that has to be installed on the the guest OS. This is especially important if a database is running inside the VM.
Snapshots are great to capture the state of the full system and you can easily restore or migrate your full setup. With rsync, you can store files continuously and if you have trouble with some specific files, you can more easily find a specific file (perhaps of a previous version) without restoring the whole setup.
That’s why I do both