Both goals came from Cody Gakpo assists at Portman Road, handing Andoni Iraola his first Premier League win since taking over as Liverpool manager this summer.
Isak's early double settled the contest before half-time, and the visitors were rarely troubled thereafter as they controlled the second half to see out a comfortable, professional victory.
Ipswich Town boss Gary O'Neil used his post-match press conference to raise concerns about refereeing standards more broadly, pointing back to his side's 5-2 defeat at Manchester United the previous weekend.
"We have been told a lot about needing to cut down on time-wasting," he said. "My goalkeeper is pressured into kicking the ball quickly at Old Trafford, even when we aren't even ready, and I felt Liverpool found it far easier to run down the clock here."
O'Neil added that the inconsistency had frustrated him.
"It irritated me a little. They could easily have been pushed to get the game moving faster," he said, according to Sky Sports.
Despite that complaint, O'Neil was otherwise complimentary about the officiating at Portman Road, including a VAR intervention in the 70th minute that overturned a Liverpool penalty appeal after Dominik Szoboszlai was ruled offside in the build-up.
"I think overall the officials did well," he said. "VAR also reached the right decision on the penalty incident."
Isak's brace continued his rapid recovery from an injury-hit debut season at Anfield following his British-record £125m move from Newcastle United, and took him to three goals in as many Premier League appearances this campaign.
Liverpool also handed a debut off the bench to record signing Bradley Barcola, who arrived from Paris St-Germain for £123m over the summer, as Iraola's side put back-to-back winless league games behind them.
Isak's opener on six minutes squeezed through the palms of Ipswich goalkeeper Kjell Scherpen, before the same combination doubled the lead three minutes later when Scherpen was caught out by a long ball and beaten by a low finish.
It continued a productive personal record at Portman Road for the Sweden international, who had scored a hat-trick there during his time at Newcastle. Ipswich improved after the break, with Abdul Fatawu Issahaku and Julio Enciso offering some threat, but they could not find a way past a well-organised Liverpool backline.