Yes, you can use the iPhone 13 in Spain without any major problems. Here are some key points to consider:

- Dual SIM and eSIM Support: The iPhone 13 supports both physical SIM cards and eSIMs, allowing you to use a local SIM card or a prepaid eSIM plan to avoid high roaming charges.
- Network compatibility: Make sure your iPhone is compatible with the frequency bands used in Spain. Most iPhone 13s are compatible with 4G and 5G networks in Spain, but it's always a good idea to check with your operator.
- Activation and configuration: If your iPhone is unlocked, you can add multiple eSIMs and bundles via local operators. You can configure and switch between different data lines via your iPhone settings.
- WiFi Calling: In poor cell coverage, you can use WiFi Calling for better quality calls.

All in all, the iPhone 13 is perfectly usable in Spain, especially with the dual SIM and eSIM options that make it easier to manage local connections.