Process plugin for stripping out characters

I am using Migrate CSV to migrate sharepoint nodes from a csv file into Drupal 8
I need to strip part of the page titles. An example page title is about.aspx. I want to strip the .aspx
Right now I am doing a straight mapping like this= title: title. Is there a plugin that can strip this out?
I know I could do a search and replace in the csv file but I feel its safer to remove in the processing.
I have looked here but cannot find one.
https://www.drupal.org/docs/8/api/migrate-api/migrate-process/
also is there a plugin that can add content. Or Prefix and Suffix. Example is the body section I am mapping over straight has no html. I would like to Prefix and Suffix the paragraph tag <p>my body section needs html tags</p>

Drupal version: 


Source: https://www.drupal.org/taxonomy/term/37/feed