Answer: The Gemara (Berachos 41b) teaches that wine exempts other drinks. Tosafos explains that as wine is such an important drink, any other drink is considered taful, insignificant in comparison. Thus, the Shulchan Aruch (OC 174:2) writes that saying the beracha hagefen on wine exempts one from saying a beracha on other drinks. The Mishna Berura (174:3) writes, however, that this only applies when the drinks are either on the table or one intends on having another drink at the time when one says hagefen.
If one heard kiddush from another but didn’t drink wine themselves, they should say shehakol before drinking another drink. There is a machlokes, however, as to whether one who hears kiddush from another and only sips a little, needs to say a beracha on other drinks. R’ Ovadia Yosef (Yechave Daas 5:20) writes that other drinks are covered even if one has just a sip of wine. The Mishna Berura (Biur Halacha 174:1), however, writes that as there are different opinions, one should drink at least melo lugmav, a cheekful (at least 1.6oz). If one drinks less, there is a safek, doubt, as to whether other drinks are covered or not (See Minchas Yitzchak 8:19). One who drinks so little should either say shehakol on some food before drinking or listen to another person say shehakol.
R’ Moshe Sternbuch (Teshuvos Vehanhagos 1:264; Moadim Uzemanim 3:243) quotes R’ Yitzchak Zev Soloveitchik that one does not fulfil their obligation of daytime kiddush by listening to another recite it unless they drink some wine. R’ Ovadia Yosef, however writes that this is not necessary.
In conclusion, if one wants to have a drink at a kiddush then it is best if they don’t drink any wine first. Alternately, they should either ensure that they drink a melo lugmav, say shehakol on some food first, or listen to someone else say shehakol.