Can I replace iPhone with an iPad mini?

An iPad, whether a Cellular model or not, is not capable of directly accessing Cellular Voice or SMS/MMS Messaging features. An iPad with either WiFi or Cellular connectivity alone can only access IP-data services. If you have added an eSIM or physical DataSIM and Cellular plan to a WiFi+Cellular model of iPad, the number associated with the eSIM/SIM card is only used to identify your account for billing purposes. This number is cannot used for making calls or sending messages; an iPad is not, and can never be, a standalone substitute for an iPhone.

However, when coupled with an iPhone, the capabilities of iPad significantly broaden to include access to Cellular Voice and Messaging services of the associated iPhone - relayed to the iPad over WiFi using Apple’s continuity features. As such, cellular calling and messaging capabilities of the iPhone are extended to the associated iPad.

More information about Continuity and the relevant Cellular services can be found here:

Continuity

Use Continuity to connect your Mac, iPhone, iPad, iPod touch and Apple Watch – Apple Support

SMS/MMS Messaging

How to forward SMS/MMS text messages from your iPhone to your iPad, iPod touch or Mac - Apple Support

WiFi Calling

Make a call with Wi-Fi Calling – Apple Support

I’m going to be the “wrong” answer. I never had an iPhone, up until I got my iPad mini, I used iPod touches. My touch does not have cellular abilities. If I am connected to WiFi, I can do 99% of the things my BF does on his iPhone.

I have a google voice number that I can use to call or text. I can surf the web. Etc. I’ve been doing this for years and was very disappointed that the iPod touch was discontinued, the only reason I got an iPad mini.

I do have a cell phone, it’s a flip phone that was less than $100 and has the ability to be a hotspot.

So yes, you can do this. It won’t be a cellphone but with a WiFi signal it will be pretty close. You can probably use any VOIP service for this.

Bear in mind an iPad is not a cellular telephone. Its cellular capabilities are used exclusively for cellular data.

it will never be able to receive voice calls or sms's without an iPhone connected to the same appleID

To add to and not to muck up these excellent replies. To make phone calls on the iPad you need an iPhone. Just like the Apple Watch (but more) you need an iPhone.