Wow… ehmm… using F2FS for your operating system is not a great idea - for a PC. F2FS was designed for IoT devices that you aren’t supposed to mess with, and may be useful for other edge cases - if you know exactly what you are doing, which I’m assuming isn’t the case because of this post…
So - to sum it up: you cannot resize a partition with an F2FS file system.
If you want a different partition layout - for example if you want to install another operating system on the device - you will need to reformat your drive and re-install all the operating systems, after designing your layout to account for both operating systems.
BTW - which Linux operating system are you using, that installed the system partitions on F2FS? I really want to know so I can tell all my friends not to use it…