Please read this older Discussion: Keys stopped repeating - ???
It's allegedly supposed to work the way you describe: Set how quickly a key repeats on Mac - Apple Support, although I have found the behavior to be at least somewhat application-specific. For example repeating keys do not work on this Mac using Safari and this site, but it does work in the Terminal app. The reason could be that Terminal has no use for accented characters.
Notice that Apple Support document refers only to "certain" keyboard keys. It doesn't specify which. Some characters will repeat, for example dash dot * and so forth, but letters and numerals will not. There doesn't appear to be a way to circumvent that behavior other than to resort to defaults write commands which is hardly convenient.
It may be worthwhile to try an NVRAM Reset, but I doubt it will work because I surmise that is the way Apple wants macOS to work: Reset NVRAM or PRAM on your Mac - Apple Support.