Chosen Solution

I got a 128gb, not powering on iPhone 7 and a perfectly functioning iPhone 7 32gb. Could I swap the logic boards to make the functioning iPhone 7 have 128gb? I’d also swap the home button as well

You would need to swap the nand over. But it is not that simple, you need to remove the 32GB nand put it in a nand programmer read and write the device info off it, then put the 128GB nand in the programmer and write the info from the 32GB nand. This procedure needs to be done by a board level repairer.