the bootstrap package do not add custom html afaik. it adds simply bootstrap classes to anchors.

<a class="btn btn-success" href="t3://page?uid=8">test</a>

this can be done via the config.yaml of your ckeditor config in the styles section.

see https://docs.typo3.org/c/typo3/cms-rte-ckeditor/main/en-us/Configuration/Examples.html (edited)