There are many kinds of magic. Take a look at what exists in Tolkien's world. No rules, or almost none, yet it *feels* powerful in that world. Or look at what Piers Anthony did, where each person can do only one specific bit of magic and sometimes it's incredibly trivial, like the ability to make a fart sound. Systems like Le Guin's Earthsea can be elaborate without having a whole bunch of rules. There is, in fact, no particular reason why you have to have teleportation exist at all. You can still have magic. Then there's god-based magic where people have to pray for magical effects, never knowing quite what they'll get.
All and any of that can exist in a 21st century setting. Steampunk showed the way on this. You just invent one or more magical substances to power your machines.
The range of solutions and approaches really is quite broad. The more fantasy you read, the more you will discover.
All and any of that can exist in a 21st century setting. Steampunk showed the way on this. You just invent one or more magical substances to power your machines.
The range of solutions and approaches really is quite broad. The more fantasy you read, the more you will discover.