Sounds like a good follow up to the discussion in the previous thread ([Columns order and object alignment] (Columns order and object alignment)).
On the most basic level there is “col-xs-6” which will be two columns across all breakpoints. I have shown a basic RAW HTML example (Not a Blocs example), I assume this is what you mean?
In the meantime you could maybe do your own manually with the HTML widget Bric, or manually after export. However you will probably have to contend with any CSS overrides that Blocs has in place already as well, concerning styling or create your own in addition to get it how you want.
So as @mackyangeles says, “more structure blocs” or even better to have the ability to set the desired structure for Blocs and Brics via the UI concerning the Bootstrap Grid Classes, push & pull, etc., or a more expansive use of the Bootstrap Grid in available Blocs/Brics.