How to resize boot partition?

As the root partition is separated from the unallocated space you could delete the swap partition though you will first have to use swapoff from a right click. secondly delete the extended partition and finally enlarge the root partition into the unallocated space except for a new swap partition at the far right end.

This will take a long time and you must not interupt the activity or you will probably lose everything.

A better way to proceed is just to create a new ext4 partition in the currently unallocated space and mount that using fstab. You can then use that partition for data files. It is possible to use symbolic links to the data folders in your current home so that all files appear to be sited in your home even though they are in that data partition.