Translation:What do you drink?
If you said something like "請問你喝什麽?" I would interpret it as "Excuse me, what are you drinking" If I wanted to know what this person wants to drink I would add the word 要 or 想 in front of the verb.
It's important for foreigners to also recognise that Chinese verbs like English ones tend to be in a present continuous form. Some might argue that it's only present form when you add 在 in front of the verb, but people tend to just interpret it as present tense regardless of whether you add 在 or not. Other tenses would use characters such as 會 and 了.
I would say though, the use of 想 is more prevalent in HK affected Chinese (I'm from HK), whereas with Mainland Chinese it's more common to use 要 when you ask someone what they want.
Also, not many people use 甚 for 甚麼 even in regions that use the traditional Chinese script. You're not wrong to use it, but most people use 什 for 什麼. There are phrases where you can only use 甚 but this isn't one of them. It's the same as the traditional character for 十 which is 拾. It's the traditional character for it but no one uses it except during scenarios such as banking.