There is no definitive answer to this question as it largely depends on the specific rules and regulations of a particular casino. In general, however, it is generally accepted that a blackjack dealer must hit a soft 18 in order to maintain the house edge.
This means that, on average, the house will earn money from every blackjack hand played at a casino. If a dealer does not hit a soft 18, then they are likely giving their opponents an unfair advantage and could potentially lose money for their casino.
There are some casinos, however, that may allow dealers to “lean” or “push” if they are feeling confident about their hand. In these cases, the dealer would still hit a soft 18 in order to give themselves an edge, but would concede if their hand was not good enough to win outright.
Ultimately, it is up to the individual casino how they want to handle dealer’s hits and misses. While most casinos require dealers to hit a soft 18 in order to maintain the house edge, there are some that permit dealers to lean or push if they feel confident about their hand.