21.5 4k iMac 24gb SSD only replacement

Hello All,

Just to start off -- I purchased 21.5 4k with the 1TB Fusion Drive. I knew it only came with the 24gb of SSD. I also know its a 32gb blade. I knew based on iFixit and other teardowns that it is possible to replace the hard drive. I also understand that the SSD is a PCIe blade separate from the HD. I know how difficult it is to get inside and it can void my warranty. I know there is a external SSD route. I am past the return window as well. I've researched different sites and people tend to go off topic and couldn't find a definite answer.

My question is quite simple -- Can I replace the 24GB SSD blade and replace it with a higher one? Leaving the HD alone. Just replacing the SSD.

I've having some hiccups so I just want to know ALL of my options.

Thank you