Property 'value' does not exist on type 'Readonly<{}>'

The Component is defined like so:

interface Component<P = {}, S = {}> extends ComponentLifecycle<P, S> { }

Meaning that the default type for the state (and props) is: {}.
If you want your component to have value in the state then you need to define it like this:

class App extends React.Component<{}, { value: string }> {
    ...
}

Or:

type MyProps = { ... };
type MyState = { value: string };
class App extends React.Component<MyProps, MyState> {
    ...
}

interface MyProps {
  ...
}

interface MyState {
  value: string
}

class App extends React.Component<MyProps, MyState> {
  ...
}

// Or with hooks, something like

const App = ({}: MyProps) => {
  const [value, setValue] = useState<string>('');
  ...
};

type's are fine too like in @nitzan-tomer's answer, as long as you're consistent.

If you don't want to pass interface state or props model you can try this

class App extends React.Component <any, any>