How to truly change file extension (=filetype) on ipados/ios

Prior to ipados/ios 16 it was (nearly) impossible to truly change a file’s extension natively. There’s a lot of misinformation/misunderstanding on how/whether this can be done. For example, an attempt to rename text.txt to text.html merely changed the true filename to text.html.txt, but did not change the filetype.

As of ipados/ios 16, one can natively change a file’s extension(type). In Files, select the folder which contains your target file. Select the Folder Options icon (three dots/lines), choose “View Options”, then “Show All Extensions”. In this context you can now use Rename to edit/change the actual extension. You get a confirming indication that this is doing what you intend by a warning that the change may prevent the file from being read by the original filetype’s app. (at least in ipados/ios 17.2.1)