You will need to use a computer that understands the Linux ext4 file system to expand the Boot partition. If you don't use Linux or Raspbian daily, you can also use the extFS extension (not free) that is available for both MacOS X and Windows.
Be mindful that if you do that, it will take proportionately longer to save and restore the microSD card to the point it is not worth it. As it is, the 32 GB image already takes about 5 and a half minutes to restore from a computer. A 256 GB microSD image would take almost an hour to restore.
It is much better to use the Raspberry Pi's file system through the USB port to store your images and system logs. Many fast USB sticks can benefit from using the USB 3 port. On a Raspberry Pi 4 (ASIAIR Pro), a fast USB 3 flash memory should also be faster than the microSD.
The additional advantage is that USB memory is less fragile than the microSD card when you repeatedly remove and insert the memory, especially if you go through a USB 3 Hub so you don't wear down the USB 3 socket in the ASIAIR Pro..
I have also used the Samsung T5 series SSD successfully (I have tried both 1TB and 2TB versions, and Samsung also sells a 512 GB version of the T5). The advantage of the Samsung T5 is that it uses very low power, and can can work through USB 3 power, and it is even faster than most USB memory sticks.
Equally important, the USB drive also leaves the ASIAIR firmware alone, reducing the probability of accidentally unplugging the microSD card while it is busy writing data.
Chen