I have an application where the design calls for a 1280 breakpoint from desktop to tablet, or, xl to lg respectively. However, Bootstrap itself has the xl breakpoint at 1200
Changing the $grid-breakpoints variable will work fine. Remember that you must import /bootstrap or the bootstrap/variables in the custom.scss, and then @import bootstrap after.
For example:
$grid-breakpoints: (
xs: 0,
sm: 600px,
md: 800px,
lg: 1000px,
xl: 1280px
);
Demo: https://codeply.com/go/MlIRhbJYGj
Also see: How to extend/modify (customize) Bootstrap 4 with SASS