The US carrier has been capping the numbers to no more than 60% of capacity.
The airline is aiming to limit the spread of coronavirus and implement some form of social distancing.
Chief executive Ed Bastian told the BBC that some of the details of the plan still need to be worked out.
He said: “We will be extending the cap on the planes post-September, whether it’s 60% or a slightly higher number I don’t know, but yes we absolutely will.”
American Airlines has not limited its capacity and United Airlines has a policy to allow passengers to choose to rebook on a different flight or receive a travel credit when flights are 70% full.
More routes are returning to Delta’s schedule, with the carrier becoming the first US airline to reintroduce flights to China.
Bastian said “of course” he is worried about a second wave of the outbreak as cases of Covid-19 are now estimated to have passed 20 million in the US.
“I’ve said throughout this pandemic that it’s going to be a choppy recovery, it’s going to be stops and starts and the virus is going to move, just as people move,” he added.
Like other airlines, Delta has measures in place to try and protect those on board its flights.
“We need to make certain that we take all precautions for our people, for our customers, reinforcing wearing masks, social distancing, keeping our planes only at 60% full, making certain every seat next to a customer is open, so you have space on board, and doing everything we can to be cautious in the face of the spread,” he said.
“Because until there is a vaccine, it’s going to be very hard to see this industry back at scale.”
Bastian conceded that the reduction in scale will mean cutting the number of staff, which is currently around 90,000.
Those roles are all protected until the end of September under the terms of a $5.4 billion bailout plan funded by the US federal government.
Bastian said he hoped that volunteers will make the process less painful.
“We’re doing everything we can to hold on to as many jobs as possible, and while the job count will go down, our goal is to make it as voluntary for employees as we can.”
Thousands have signed up for early retirement while 37,000 others are taking time off without pay, in periods ranging from 30 days to a year.