Most built-in back-ends come with a command to convert the selected region into a selected format and replace this region by the exported output. Here is a list of such conversion commands:
This is particularly useful for converting tables and lists in foreign
buffers. E.g., in an HTML buffer, you can turn on
use Org commands for editing a list, and finally select and convert the list
M-x org-html-convert-region-to-html RET.