Is it possible to resize mounted partition over ssh?

Background: I was given SSH access to a Ubuntu 20.04 VPS that has root partition of 5G (sda total 25G). VPS provider says Linux admin can resize the /dev/sda1 partition.

$ sudo fdisk -l && df -hDisk /dev/sda: 25 GiB, 26843545600 bytes, 52428800 sectorsDisk model: Virtual disk    Units: sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisklabel type: dosDisk identifier: 0xe1f10bb0Device     Boot Start      End  Sectors Size Id Type/dev/sda1  *     2048 10483711 10481664   5G 83 LinuxFilesystem      Size  Used Avail Use% Mounted onudev            1.9G     0  1.9G   0% /devtmpfs           394M  788K  393M   1% /run/dev/sda1       4.9G  3.0G  1.7G  64% /tmpfs           2.0G     0  2.0G   0% /dev/shmtmpfs           5.0M     0  5.0M   0% /run/locktmpfs           2.0G     0  2.0G   0% /sys/fs/cgrouptmpfs           394M     0  394M   0% /run/user/1002

I need to resize /dev/sda1 partition mounted to / over SSH. As far as I know, it is not possible.

Is it impossible, is it possible or has there been some miscommunications with the VPS provider? I am in contact with them through a third party.