Create an EFI partition while installing Ubuntu 21.04 in another disk partition

How can I create an EFI partition while installing Ubuntu 21.04 in another disk partition where I also have Windows 10 installed?

tl;dr: Ubuntu can utilize your existing EFI partition. You also need to make sure that your new Ubuntu partition is formatted with a GPT partition table. The installer handles the rest automatically.

1. Use an Ubuntu live USB to boot your computer.
2. Connect to the internet
3. Use the apt package manager to install gparted. You may need to update & upgrade first`.
4. When you open gparted, see if a there is a small EFI partition beside your Windows partition. If there is not, your hardware probably doesn't support BIOS. If an EFI partition is there, your Ubuntu installer will automatically use that one.
5. Resize your Windows partition with gparted. Leave at least a bit of extra space in the Windows partition.
6. Use the fdisk utility to format the remaining partition to a type of linux filesystem and to a GPT partition table - NOT DOS/MBR. Make sure to write your changes to disk. (Lots of great fdisk tutorials on YouTube if this part sounds like Greek). 7.Run the installer on your new formatted partition. Since you have a GPT partition table and and existing EFI partition you'll be set.