Multiple template pages when creating new pages
Option 1:

The simplest "core" way to do this, is to create two separate content types.  For this example, let's call one One Column and the other Two Column

You can now create two different node template files:

node--one-column.tpl.php
node--two-column.tpl.php


Now you can customize those two template files to display the content however you wish, and it would depend on what you want to accomplish with each of these.

Option 1a:

If you decide to go with option 1, using Paragraphs to allow your users to add multiple fields into the columns could be well suited to your needs.

Option 2:

Another option is to use Display Suite which has the similar idea of creating multiple template files, but here you can choose the display method on a per node basis (via Display Suite Extras)  Also since you are using Bootstrap, there is a nice add-on called Display Suite Bootstrap Layouts that provides layouts for you to use.

Option 3:

Panalizer allows you to use "Panels" on a per node basis, which could help you solve this problem. There is also a Panels Bootstrap Layouts module as an add-on.

Option 4:

I believe Panopoly can do this as well.

Summary:

There are many different ways to do this, but you will have to try them out to see which works best for you.  The options above are probably the most common so I'd start there.  If you need anything more specific for your needs, there is always a way.