Requirements: Termux, Root (preferably Magisk).
Open termux and give it root permissions
Type su to escalate the permissions
Now enter the command dd if=/dev/zero of=swapfile bs=1024 count=6144k replacing 6144k with as much swap as you need, in this case 6GB
Once its done, enter mkswap swapfile to create the sawp file and swapon swapfile to enable the swap file
what about non-rooted phones ??