In purchasing a WiFi+Cellular model of iPad, you are not committing yourself to needing a Cellular Carrier plan - but are preserving the opportunity and flexibility of doing so at a later time. If you only need occasional cellular use for infrequent travelling, you may be able to configure a short-term plan directly from iPad settings - or obtain a pay-as-you-go plan from your chosen cellular provider.
Set up cellular data service on your Wi-Fi + Cellular model iPad - Apple Support
Also be aware the only WiFi+Cellular models have GPS location functions. WiFi Only models do not have any built-in GPS capabilities - which may be important to you for real-time mapping applications. While GPS is a function of the iPad cellular chipset, GPS is entirely independent of cellular.
The potential need for GPS positioning capabilities is just one of the many reasons that some users choose a WiFi+Cellular model in preference to WiFi Only models - even if having no need or intention of using Cellular.