I am looking on eBay for an iPad Pro 10.5” model and in the original Apple website it clearly says that both Pro versions 10.5” and 12.9” comes with Wi-Fi + Cellular connectivity. But many of the sellers in their descriptions point out that it is Wi-Fi only. I do not understand - should the iPad Pro 10.5” come with Wi-Fi + cellular or only Wi-Fi?
The iPad Pro, regardless of whether it's the 10.5" or 12.9" size, comes in two main configurations - one with Wi-Fi only and one with both Wi-Fi + Cellular.
The reason many of the sellers are pointing out that the model they're selling is Wi-Fi only is because that's the configuration they're selling.
For more detailed information I refer you to the specs provided on Apple's website. You'll see that there are details for both the Wi-Fi models and the Wi-Fi + Cellular models. For example, you'll see differences listed under Size and Weight and so on.