Вам больше ничего не нужно?

Because нужно normally goes with the dative case to show who something is necessary for.

So вам literally means to you / for you, not you as a subject.

Russian often says things like:

• Мне нужно — I need
• Тебе нужно — you need, informal
• Вам нужно — you need, polite or plural

So the structure is not like English you need.... It is closer to for you, it is necessary....

Here больше means any more, anything else, or further depending on the context.

It does not literally mean only bigger here. Compare:

• Мне больше не нужно — I don’t need any more
• Вам больше ничего не нужно? — You don’t need anything else?

So больше adds the idea of additional or further need.

Yes, it is a double negative by English standards, but that is normal and required in Russian.

Russian commonly uses negative concord, which means that if you have a negative pronoun like ничего meaning nothing / anything, the verb or predicate is also negative:

• Я ничего не знаю — I know nothing / I don’t know anything
• Никто не пришёл — Nobody came
• Вам ничего не нужно — You don’t need anything

In standard Russian, ничего нужно without не would be wrong.

Because after нужно, Russian uses the form ничего, which is the genitive form of ничто.

This is part of how Russian expresses absence or negation in many structures. After negation, Russian often uses the genitive:

• У меня нет времени — I have no time
• Я не вижу ничего — I don’t see anything
• Вам ничего не нужно — You don’t need anything

So ничто is the dictionary form, but ничего is the form actually used here.

Because this sentence uses impersonal нужно, not the adjective нужный agreeing with a noun.

In Вам больше ничего не нужно?, there is no specific noun being described. The idea is simply Is anything else necessary for you?

So нужно stays in its fixed neuter form.

Compare:

• Вам нужно что-нибудь? — Do you need anything?
• Вам нужен пакет? — Do you need a bag?
• Вам нужны документы? — Do you need the documents?

When a specific noun is present as the thing needed, Russian often uses agreement:

• нужен for masculine
• нужна for feminine
• нужно for neuter
• нужны for plural

But in your sentence, нужно is part of an impersonal pattern.

It can be either:

• polite singular — when speaking respectfully to one person
• plural — when speaking to more than one person

Russian uses вы / вам both for:

1. more than one person
2. one person in a formal or polite situation

So in a shop, restaurant, clinic, hotel, or other service context, Вам is usually polite singular unless the speaker is clearly addressing several people.

Yes. Russian word order is flexible, and small changes can shift emphasis.

These are all natural:

• Вам больше ничего не нужно?
• Вам ничего больше не нужно?
• Ничего больше вам не нужно?

The first two are the most common.
A rough difference:

• Вам больше ничего не нужно? — very neutral
• Вам ничего больше не нужно? — also neutral, with nothing else a bit more grouped together
• Ничего больше вам не нужно? — stronger emphasis on nothing else

In everyday service situations, the original version sounds very normal.

It is polite, but not especially stiff or official.

Because it uses Вам, it sounds appropriate in situations like:

• a cashier speaking to a customer
• a waiter speaking to a guest
• a receptionist helping someone
• a pharmacist or doctor asking a patient

If you were speaking to a friend, you would usually say:

• Тебе больше ничего не нужно?

So the level of formality mainly comes from Вам rather than from the rest of the sentence.

Both are very common, but they feel slightly different.

• Вам больше ничего не нужно? — You don’t need anything else?
• Вам что-нибудь ещё нужно? — Do you need anything else?

The second version is often a bit more straightforward and less negative in structure. The first can sound slightly more like That’s all, right? or No other things needed?

In many contexts, they are practically interchangeable.

Also note:

• ещё often means still / yet / else / more
• больше here means any more / else

So Russian has several natural ways to express this idea.

A very common reply is:

• Нет, спасибо. — No, thank you.
• Да, пожалуйста... — Yes, please...
• Нет, больше ничего не нужно. — No, I don’t need anything else.
• Да, мне ещё... — Yes, I also need...

This can be tricky for English speakers because it is a negative question. In Russian, people often answer according to the real situation:

• Нет = No, I don’t need anything else
• Да = Yes, I do need something else

So in a shop, if you are finished, Нет, спасибо is the most natural answer.