yocto image size gets increased with increase in partition size

Question

I am creating an empty partition for my yocto image file(.wic) by adding below line to directdisk.wks:

part /opt --use-uuid --fstype=ext4 --label user --align 1024 --size 1024

Able to create a partition but the image size gets increased i.e. image size + partition size. let's say, I have created empty /opt partition of 1GB, then 1.53 GB(initial image size) + 1 GB(/opt) = 2.53 GB(new image size). My concern is what happens with a 128 GB SSD allocated fully with partitions. Will the image size be 128 GB?

Is there a way to generate .wic unaffected with empty partition size?