Sample text file: Windows-1252 (legacy "ANSI" encoding)
Free sample from 99helpers.com/file-types/txt

This file is NOT UTF-8. Each character is exactly one byte, using the
Windows-1252 code page that Western-European Windows used for years.
Line endings are CRLF.

Opened as Windows-1252 (or "Western"), these read correctly:
  Café crème, naïve, Zürich, Ærøskøbing, São Paulo, Ångström
  Price: €12.50 (the euro sign is byte 80)
  Quotes: ‘single’ and “double” (bytes 91 92 93 94)
  Dash and ellipsis: – — …

Opened as UTF-8, those bytes are invalid, so most programs show
replacement characters (a question mark
in a black diamond) instead. That is the classic sign of a
file in an old 8-bit encoding.