A VPN can be useful when travelling for a number of reasons - not least to potentially resolve location-related issues.
If choosing a VPN provider, you should choose a reputable paid VPN service in preference to free providers. There are many from which to choose - but if looking for a fast, reliable and audited no-logging service, you might consider hideme VPN. This provider has full support for IPv6 (this being of growing importance), many country-specific points of presence and multi-hop VPN if needed.
You would be well advised to sign-up via their website - and not from the associated App that you’ll doubtless download from the Apple App Store. The subscription service is both cheaper and more flexible if you sign-up and pay for the subscription via the website.
https://hide.me/en/
As for commercial VPN services, you will likely see conflicting advice concerning their use and potential benefits…
Setting aside the occasional need to access services (such as mail) hosted in your country - and concentrating upon security and privacy - insofar as public WiFi hotspots are concerned, where your internet traffic can be both monitored and potentially manipulated by bad/malicious actors, use of a properly configured reputable VPN service is certainly recommended by knowledgable Infosec Professionals.
Public networks have a considerably higher risk profile than private networks - the latter, by design, being considerably more secure. Unknown to many, while some of your internet traffic is end-to-encrypted, some protocols (e.g., DNS) is natively transmitted “in-clear”. Unencrypted protocols can leak considerable information about your device and your activities; not only can this traffic be intercepted and analysed by anyone that shares the same network, this traffic can be manipulated and altered.
Employing a correctly configured VPN ensures that all your traffic that is transmitted on the “untrusted” public networks cannot be directly monitored or manipulated. You should note that this additional protection only extends as far as the VPN Gateway (your exit node to the internet).