How to change the encoding of a csv file before reading the csv file in Java?

I have a method that reads the content of a csv file. This works.

            CSVParser parser = new CSVParserBuilder().withSeparator(';').build();
            try (CSVReader reader = new CSVReaderBuilder(
                    new FileReader(getFilePath()))
                    .withCSVParser(parser)
                    .build()) {
                String[] lineArray;
                while ((lineArray = reader.readNext()) != null) {
                    for (int i = 0; i < lineArray.length; i++) {
                        String s = lineArray[i];
                        lineArray[i] = s.replace("\n", "");
                    }
                    sheetContent.add(new ArrayList<>(List.of(lineArray)));
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

But some Strings are not read out as I imagined. e.g.

expected output : Geschäft
current output : Gesch�fts

So I think I need to change the encoding. Therefore I check the encoding before reading.

This looks like this:

                try (InputStream inputStream = new FileInputStream(getFilePath())) {
                Charset charSet = Charset.forName(new TikaEncodingDetector().guessEncoding(inputStream));

                if (charSet.equals(StandardCharsets.ISO_8859_1)) {
                    

                }
            } catch (IOException e) {
                e.printStackTrace();
            }

In this example, the file has the StandardCharsets.ISO_8859_1, so I check for it in the if statement.

I had the idea to store the content of the file in a byte[]

                    byte[] fileContent;
                    File file = new File(getFilePath());
                    FileInputStream fis = new FileInputStream(getFilePath());

                    fileContent = new byte[(int) file.length()];

                    fis.read(fileContent);

                    byte[] data = fileContent;

and convert it via newString() to UTF-8.

byte[] utf8 = new String(data, StandardCharsets.ISO_8859_1).getBytes(StandardCharsets.UTF_8);

However, with this approach I don't get further.

Does anyone know how I can convert the encoding to UTF-8 before reading it out?