do I need a sim card for ipad 10.5 2017?

And please realize not all iPads have cellular capability, many are WiFi only. The ones with cellular cost more. Are you sure your iPad has cellular?

Yes.

In most cases, a regular mobile phone SIM cannot be used with iPad. For iPad and Mobile Broadband Routers, most Cellular Carriers will instead supply a DataSIM - explicitly provisioned for these devices.