Yes, VPNs on iPhone are generally very suitable for non-technical users, setup is usually just download, sign in, tap connect.
Performance: small speed reduction from the extra routing/encryption, but with modern protocols like WireGuard, the difference is minor for everyday use (browsing, email, social media). Streaming/large downloads may show a bit more slowdown depending on server distance, though most users won't notice this in daily use.
Battery: slightly more usage while connected, but not significant for casual use.
Good non-intrusive options: NordVPN, ProtonVPN, and ExpressVPN, clean iOS apps, one-tap connect, minimal permissions. ProtonVPN's free tier is a good zero-commitment way to try it first.