anyone?

Use a cloning software like Clonezilla, Ghost, Acronis, etc instead.

What filesystem? What size are you trying to expand to? Is it greater than 7.8GB? Keep the OS partition at or below 8GB and the other partition whatever size your controller/driver supports. You may be able to use NTLDR and netdetect.com from 2000 or XP (service packs may overwrite), can't remember but a large OS partition for NT4 isn't needed anyway.

Maybe my recent notes help you out?
Yesterday I had the same trouble (again), with my 486 VLB system which is VERY picky about SD-cards being bootable. Contrary to, for example, a 440BX system. Using it with these Sintechi SD-IDE adapters. And I could not use a bootable floppy because the system does not like floppy drives anymore. I know the 486's BIOS can handle up to 8GB cards in LBA mode.

I eventually managed to create two additional bootable SD cards for the 486, with a combination of these actions:
1- HDD-Raw-Copy-Tool running from Windows XP. Copying from an already bootable 2GB SD card.
2- Partition Wizard 9 running from Windows XP. To increase the size of the 2GB raw-copied partition.
3- The DOS 7.10 tool: "FDISK /MBR" running on a 440BX system in pure DOS.
On the first SD card action no. 3 did the trick. On the second SD card action no.3 did not help, and I only got it booting doing action no. 1 and then 2.
I am not satisfied with the trial and error involved here.
Earlier I also tried Rufus and Norton Ghost, and the MS-DOS command "SYS *Drive Letter*:" but I don't think they 'hit the spot' here.

The 486 system seems to easily trip over some mysterious data in the boot block. Maybe I should have use the tool below. Which I just found today.
Spur0Kill

Besides all tips, i found Norton Ghost amazing to clone disk and partitions, it auto expand fat,fat32 and ntfs partitions without doing nothing more than just write desire size

Anyways, i found problem in some of my computers to use more than 8GB in primary partition with NT4

I am cloning a 2gb SD to a 4GB sd. So a 2gb partition is created and the remaining space is empty.

I have tried the tool suggested above but the problem persists

But how come Windows NT does not boot into a sector-by-sector copy? I don't understand.

Assuming you are using FAT16 then NT4 uses a 64k cluster size for FAT16.
It doesn't take long to install NT4 from scratch.
Setup a 2GB or 4GB partition using FAT16 or NTFS, Install, Install latest SP, create a backup image, resize with whatever partition tool that is compatible.