Here's a flowchart based on a bulk processing capability available in the MyMail email app for Android:

1) SELECT by Keyword or Sender / 2);SELECT ALL / 3) CHOOSE A BULK PROCESS - click on desired action on menu bar or from drop down menu - Block, ±Send to Folder, *Delete
*selecting Delete pops up the proverbial warning 'Are You Sure? '
plus the NO & YES buttons

Delete &
Block Number are essential.

+Send to Folder - it would be nice if a future version of Textra includes a reasonable amount of customizable folders or perhaps additional hidden holding cells similar to Blocked Numbers