Forcing the conversion of files with different encodings to UTF-8

I have 100 files that when I issue the command file *.srt I see something like this:

file1.srt: ASCII English text
file2.srt: UTF-8 Unicode English text
file3.srt: UTF-8 Unicode text

multiple encodings... I want to convert all them to UTF-8, despite the encoding they were using.

I have tried this for a single file

iconv -f US-ASCII -t UTF-8 file1.srt > file1.new

but when I issue the command file again it still shows the file as

file1.srt: ASCII English text

I read the ASCII is subset of UTF-8 and for that reason the conversion is not being done but I want to force it.

1. how do I force the conversion to work?


2. how do I do that for multiple files?

I have tried other answers on this forum but none work and I end with the same file encodings as before.