ipad 10.5 where is sim card?

If you can’t find the SIM tray, the location for which is identified in the iPad User Guide, it follows that you have a WiFi Only model that lacks Cellular capabilities.

https://support.apple.com/en-gb/guide/ipad/ipad9940e098/ipados

Here’s an additional dedicated help page:

https://support.apple.com/en-gb/HT201337#ipad

Did you buy one which has a SIM card slot?

If so it will be on the sides.