If you have purchased a new (current model) iPad mini Cellular-model from Apple - then in many countries/regions you will be able to activate Cellular service using Apple’s embedded eSIM. In Settings you should be presented with a choice of local carriers that support Apple eSIM. You can, if you prefer, also use a physical SIM, obtained from a Carrier.
If you activate the eSIM feature, you will not receive a physical SIM card - as you won’t require it (your account is activated and stored internally). You should note that eSIM plans are generally quite expensive - often considered for short term use while travelling - but can be changed, added to, or cancelled as often as you like.
iPads purchased from a Carrier often have the eSIM feature disabled - require use of a physical SIM - and are frequently locked to the Carrier Network.
You may also find these explanations useful:
https://support.apple.com/en-gb/HT203089
https://www.apple.com/ipad/cellular/
The iPad User Guide for iPadOS, available for free download within the Apple Books App, is also a useful source of information and guidance for use of your new iPad. Just search for Apple to find all the User Guides.
I hope you find this helpful in clarifying your available Cellular options.