No. The encoding is what determines that 65 66 67 should be displayed as ABC (or something else). There's nothing attached to "65" that would indicate US-ASCII should be used.

However, there are ways of determining the probable encoding.

• Searching for the BOM of unicode encodings.
• Eliminating characters sets based on the presence of non-printable or undefined characters.
• Dictionary validation. Check if the text becomes readable when treated as a particular encoding.
• Statistical approaches such as frequency analysis.

Good luck!