Do VPNs effectively prevent botnet attacks?

Hello. I have recently learnt that Internet of Things (IoT) devices are at risk of botnet attacks, which brings me concern due to the fact that I own a smart watch which connects to my Wi-Fi network. I am therefore seeking ways to protect my network from a botnet attack, and am wondering if a VPN is the way to go. Does anyone know if VPNs prevent botnet attacks? TYIA.