How to change grid from float to flex in Bootstrap4?

Question

Sass

Guys, please help.
I'm using Gulp with the wiredep plugin and Bower to include Bootstrap 4. Gulp includes the compiled css of the bootstrap. But I need to switch the grid from float to flex.
I wanted to reassign a variable in my SCSS and entered $enable-flex: true; It didn't work, because, apparently, the bootstrap's css was already compiled, and float:left was already written in it.
How to enable flex grid in this case? Through sass to compile everything with a new variable for bootstrap? Or am I missing something. It's just that there must be an easier way, there are a lot of scss files in it and you can screw up

Answer 1

The issue was resolved this way.
In the _variables.scss file I found $enable-flex: false !default; and replaced with $enable-flex: true !default; Then compiled bootstrap.scss into bootstrap.min.css file