partition

// Open GParted or KDE Partition Manager (pre-installed in many distros).
Identify unallocated space or shrink an existing partition to create free space.
If modifying an existing partition:
Right-click the partition and select Resize/Move.
Shrink the partition to make space for the new distro (at least 20GB recommended).

1. Root Partition (/)

Type: ext4
Size: At least 20GB (recommended 40GB+ if you plan to install many apps).
Mount Point: /
2. Boot Partition (/boot) (if using BIOS + MBR, you may not need this)
Type: ext4 (or EFI System Partition (ESP) if using UEFI)
Size: 512MB - 1GB
Mount Point: /boot
3. Swap Partition (Optional)
If you have enough RAM (>16GB), you may not need a swap partition.
Type: Linux swap
Size: Equal to RAM size if using hibernation; otherwise, 4GB - 8GB is enough.
⚠️ If you are on a UEFI system, make sure you DO NOT format or delete the existing EFI partition (/boot/efi). 
Just use the same one for the new distro.

Step 5: Apply Changes

Double-check your partitions.
Click "Apply" to write changes to the disk.
Step 6: Install the New Distro
Begin installation and select "Manual Partitioning" when prompted.
Assign the partitions you just created:
Root (/) → Choose the newly created ext4 partition.
Boot (/boot) → Choose the separate ext4 partition (if created).
Swap → If applicable, assign it as swap space.
DO NOT format the other OS partitions unless you want to erase them.
Ensure the bootloader is installed on the correct drive (usually /dev/sda or /dev/nvme0n1).
Step 7: Update Bootloader (GRUB)
If the new OS doesn’t appear on boot:

Boot into the existing Linux OS.
Open a terminal and run:
bash
Copy
Edit
sudo update-grub
or, if using EFI, run:
bash
Copy
Edit
sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=GRUB
sudo update-grub