iPad 9th Generation Instruction Manual and a Question

Find the correct manual here→iPad Manuals and Downloads - Apple Support

You only need a SIM if you want to use the iPad with cellular data. You can use it on Wi-Fi without a SIM.

Or do what I do, use it with the Personal Hotspot of your iPhone (assuming you have one).

Presumably you will have updated the iPad to iPadOS 17.x.

For reasons known only to Apple, a downloadable version of the iPad User Guide for iPadOS 17 is not available. However, the Guide is available online using a web browser (such as Safari):

iPad User Guide - Apple Support

The Tips App, installed by default on all new models of iPad, provides a brief introduction to your iPad - and leads you to the online User Guide. In case you missed it, here is a link to the Tips App:

https://apps.apple.com/app/tips/id1069509450

Apple also has a huge YouTube Channel - containing videos and feature guidance:

https://www.youtube.com/user/Apple

There are also comprehensive guides for Apple’s main productivity Apps, such as Numbers (spreadsheets), Pages (documents) and Keynote (presentations):

Numbers User Guide for iPad - Apple Support

Pages User Guide for iPad - Apple Support

Keynote User Guide for iPad - Apple Support

Purchase of a WiFi+Cellular model iPad does not commit you to provisioning a Cellular data plan. Many users choose a WiFi+Cellular model in preference to cheaper WiFi Only models with no immediate intention to use Cellular connectivity - principally for two reasons:

1) WiFi+Cellular models include GNSS/GPS functionality that is otherwise not available with WiFi Only models.

2) Preserves future flexibility to use Cellular data connectivity should it be required when travelling or otherwise away from an accessible WiFi network.

WiFi+Cellular models that do not have an active Cellular plan will often display a No SIM indicator. This indication is informational - and does not suggest a fault or malfunction.