By default, the block title for post-checkout product recommendations enabled by the Post-Checkout Upsell add-on is "Anything else, maybe?".
Changing it will not be a problem if you want to use a different title for this block. You can edit it as a regular language label.
To edit the title of the post-checkout product recommendations block:
Go to the "Language labels" page of your store Admin area (Store setup > Translations). Make sure the Edit labels tab is open.
Search for the label" Anything else, maybe?"
Locate it in the search results.
Click on the label name and make the changes you require.
For the sake of example, we replaced the text "Anything else, maybe?" with "Would you also like...".
Save your changes.
Note that if your store supports more than one language, you will need to check the title text for each supported language. See Translating Labels.