how do i balance bosses against large parties?
a little context, as of now we have a party of 6 level 4's, consisting of 2 rogues, a paladin, a druid, a sorcerer and a bard. in a session or 2 we'll not only be leveling up but we'll be introducing a new player to the game, a barbarian/artificer. it feels like if i throw anything at the party they'll just one-shot it or it will destroy them.
is there any tips anyone has on how to ideally balance encounters like this? i know i can add minions and such, but i havent played enough with this size of a party to know how much is too much