Expand storage space

I have an ext4 efi image, I have a 128 GB hard drive where openwrt is installed and I would like a tutorial or someone to tell me how to increase the memory of my router, which is 100 MB. I would like to take advantage of my entire hard drive.

boot gparted from a flash drive, resize the partition.

or boot openwrt from a flash drive

fire up fdisk, delete /dev/sda2, and create it again, with the new size.
exit & save (w)
resize2fs /dev/sda2


then there's [HOWTO] Resizing root partition on x86 (March 2023 edition)
or create an exroot in a new partition, instead of resizing the old.