I can’t play Fortnite because of my iPad has only 1 GB of RAM.
RAM is hardware within your iPad that is soldered in place. It can not be upgraded.
The amount of RAM depends on your model of iPad. Newer iPads generally have more RAM.
RAM is part of the system on a chip and not replaceable separately even if you disassemble iPad.
Apple A7 APL0698 SoC
Within the A7 package we find SK Hynix H9CKNNN8KTARKR 1 GB LPDDR3 DRAM