Rhetorical questions by definition are not neutral enquiries and they always carry some degree of assumption on the part of the speaker. In their mildest form they simply repeat the previous statement with a quizzical tone (with or without the interrogative particle 吗 ma ), implying that the speaker is questioning or expressing doubts about the validity of the statement. This quizzical tone is introduced (1) by stressing particular elements in the question or (2) by adding a qualifying phrase like 真的 zhēn de, 确实 què shí, etc. meaning ‘Is it true that . . .’:
他们同意了（吗）? (with stress on 同意 tóngyì)
Tā men tóng yì le （ma）?
Have they agreed?
Tā men zhēn de tóng yì le （ma）？
Have they really agreed?
你喜欢喝茅台（吗）？ (with stress on 茅台 máotái – a strong Chinese liquor)
Nǐ xǐ huān hē máo tái （ma）？
You like (drinking) Maotai?
Nǐ què shí xǐ huān hē máo tái （ma）？
Do you really like (drinking) Maotai?
 Yip, P. C., Rimmington, D., Xiaoming, Z., & Henson, R. (2009). Basic Chinese: a grammar and workbook. Taylor & Francis.