I use the minimal Photon distribution and it seems the system disk is only around 8GB.
That fills up quickly when installing some humongous Docker containers :/
List usage
1 | df -h |

Check available space on disk
1 | fdisk -l |

Install Diskpart
tdnf install parted

Diskpart
1 | parted |

Increase size
1 | resizepart |
1 | print free |

Reboot
1 | reboot |
Resize filesystem
1 | resize2fs /dev/sda2 |
1 | df -h |
And a reboot just for good measure
