You can use the Bootstrap 4 utility classes to adjust the layout...
h-100 to make the left card full-height to match the smaller cards
p-2 spacing (padding) to make even gutter between columns
https://www.codeply.com/go/CPe58ZHi2u
Test 1
Test 2
Test 3
Test 4
Test 5
Test 6
Test 7
Also, p-3 could be used instead of p-2 if you want a larger gutter.