Understandably this is playoff basketball so totals are going to be low. But the Celtics aren't playing the Raptors here. Miami isn't the defensive team that Toronto was. 
The Celtics are sure to be fired-up after blowing huge leads in the first two games to fall behind 0-2. If Boston builds up another big lead it won't coast. The Celtics will stay on the attack. There's also the chance Gordon Hayward makes his series debut. That would give Boston a legitimate fourth scoring weapon to go with Jaylen Brown, Jayson Tatum and Kemba Walker, who shot much better in Game 2. 
The Heat defense got through the Bucks because Milwaukee lacked a quickness advantage. The Heat don't have that edge on the Celtics.
Miami, though, has been getting the needed contributions from players besides Jimmy Butler. The Heat scored 106 in the last game despite Butler shooting just 4-of-11 from the floor and scoring a meager 14 points. Miami's motion-laden offense has been successful exploiting Walker's weak defense. 
The Heat have averaged 109.7 points in regulation during their last seven games facing the Celtics and Bucks, who gave up the eighth-fewest points and ranked first in defensive field goal percentage during the regular season.  
If the Heat are able to build up a big lead, I could envision a bubbling-over frustrated Celtics team committing a lot of fouls.