दौड़ना is a regular verb in Hindi. So, it has all the tense forms that other verbs have. दौड़ता है in the simple present tense (runs), दौड़ रहे है in the present continuous (is running) and so on.
However, 'sitting' and 'standing' are not seen as actions in Hindi but as states. So, their Hindi counterparts are adjectives rather than verbs. As a result, the sentences राज खड़ा है and राज बैठा है work more like the sentence राज अच्छा है ('Raj is good') than the above sentence with दौड़ना. But since 'sit' and 'stand' are verbs in English, they are translated into English in their present continuous forms 'Raj is standing' and 'Raj is sitting'. You can instead think of them as 'Raj is upright' and 'Raj is seated' if it helps any.
Note: बैठना is a verb but it refers to the action of sitting down (ie, going from the state of standing to the state of sitting). So, राज बैठ रहा है means 'Raj is sitting down' rather than 'Raj is sitting'/'Raj is seated'.