Yes you can use more that 255 characters in a text file.
What version of Access are you using?. I am using Access 2013 & below is a copy from the help files that may help you. In older versions of Access you would use a Memo for long text, but Access 2013 now calls it Long Text.
The Memo data type is now called “Long Text”
In earlier versions of Access, we used the Memo data type to store large amounts of text, and the Text data type to store shorter strings (up to 255 characters). In Access 2013, these two data types have been renamed “Long Text” and “Short Text” respectively, and they have different properties and size limits depending on whether you’re using a desktop database or an Access App. Here are the details:
Text fields in desktop databases (.accdb)
Long Text In .accdb files, the Long Text field works the same as the Memo field of old. That is, it can store up to about a gigabyte of text, even though controls on forms and reports can only display the first 64,000 characters. You can set Long Text fields to display Rich Text, which includes formatting like bold and underline.
Short Text In .accdb files, the Short Text field works the same as the Text field in earlier versions. It stores up to 255 characters.