Add T-Mobile wifi to my car

I have a 2019 BMW with WIFI which is not connected to any service.  My phone works just fine using the on board programs to make and receive phone calls- most of the time.  I have a place in remote North Central Wisconsin that has very poor phone reception.  There are few T-Mobile towers, but just a few. In town, Minocqua, I cannot make or receive calls unless I hook up with a business with WIFI.  Cellular calls are not available.  I was wondering if I activate my in car WIFI, would this afford better remote reception?  Would the car antenna afford better cell reception?

   I am NOT a whiz with this stuff, being closer to 100 years old than to 50.  I went to T-Mobile and signed up for DIGITS.  I have no clue if this is what I want???

I would appreciate any instruction, advice or guidance with this.

Thanks.