Since Ionic and Bootstrap css can have conflicts between them we cannot fully support bootstrap classes on Ionic. However we're going to add more and more support to specific classes in a near future.
Please follow the following issues to keep up with this topic:
Ionic mobile components can be found on https://ionicframework.com/docs/components/ but they are not supported on website.
Some bootstrap components are supported on mobile but we're working on adding more of them.