If you own an older home, you can still benefit from smart home technology. Most smart devices connect wirelessly, so your main sticking points will be coverage and connectivity. As long as you have Wi-Fi extenders or smart home connected devices that create a mesh network, you can enjoy the benefits of home automation.
The former solution—a basic Wi-Fi network—may or may not produce desired results. Some older homes have odd corners, thick walls, or other obstacles that can hamper Wi-Fi coverage, no matter how many extenders and repeaters you buy. In those cases, opting for a smart system that creates an internal mesh network might be better. Zigbee and Z-Wave both employ mesh networks and rely on frequencies other than those used by Wi-Fi, so those could be good alternatives.