This is the parliamentary term when New Zealanders - and her millions of fans abroad - get to know the prime minister, what she believes and what she can achieve.

A historic mandate in Saturday's election means Ms Ardern has more power than her modern predecessors John Key and Helen Clark, entrusted with a parliamentary majority for the first time in three decades.

Labour's first-term "handbrake" of working in coalition with two other parties, the Greens and New Zealand First, is now off.

Ms Ardern is also unchallenged within her own party, given her surprise 2017 success and the scale of 2020's victory.

So how will she use this power?

Ms Ardern has left clues in comments before and after the election.

Firstly, she is a consensus-builder by nature.

With 64 seats in the 120-member house, Labour doesn't need to govern with others, yet it is meeting with the Greens to ponder a power-sharing deal.

On Tuesday, Ms Ardern said she wanted to "use the strengths that exist in their team", which could mean handing the minor party portfolios.

Part of this is practical; Labour has a sweep of inexperienced MPs and Ms Ardern could do with some ministerial help.

Another part is philosophical.

In an interview with Australian Associated Press, Ms Ardern said time in opposition watching Mr Key's National government unwinding Labour initiatives taught her the value of coalition-building.

"Reflecting on New Zealand's history, the things that stick, that you want to be transformative, surely you don't want to just be transformative for a 24-month, or 36-month period," she said.

"It's about getting people to actually hang on to something because it's something they broadly agree with and they won't be disestablished the moment you're out of government."

Ms Ardern is proud of getting opposition support for two of her signature achievements to date - child poverty and zero carbon legislation.

Reaching out to the Greens and to the opposition is a trend she's likely to follow in her second term.

Secondly, Ms Ardern is cautious, particularly so in the COVID environment.

Ms Ardern's government is taking a health-first approach to COVID-19, winning support at home and across the globe by eliminating the virus and returning everyday life largely to normal.

That cautiousness was on display during the election campaign, when Labour campaigned without reformist plans.

Labour released a manifesto full of motherhood statements just four days before election day after a million New Zealanders had already voted and without trailblazing promises of major change.

The manifesto included almost no policies with targets, reflecting Ms Ardern's toughest political moments to date have come after her government fell short of its promises on homebuilding, light rail and child poverty.

This means Kiwis understand the values of the government but know little of its big-picture plans.

Importantly too, the government is broke.

Finance Minister Grant Robertson's carefully rebuilt surplus is a distant memory thanks to the government's economy-saving measures, and there is pressure to keep debt in check.

The recession means borrowing is cheap but the government will resist it; even before the arrival of COVID-19, Ms Ardern was no spendthrift.

Faced with straight-forward but expensive measures to reduce poverty and inequality from a report the government commissioned into welfare reform, it opted instead to tinker at the margins.

While Ms Ardern promises transformation, she's delivering incrementalism, which may or may not blossom in the next three years.

Thirdly, Ms Ardern isn't likely to lurch New Zealand to the left.

Ms Ardern calls herself a "pragmatic idealist", but her election night pledge to "govern for every New Zealander" was instructive of a centrist positioning.

"Governing for every New Zealander has never been so important ... we are living in an increasingly polarised world, a place where more and more people have lost the ability to see one another's point of view," she said.

"We are too small to lose sight of other people's perspective. Elections aren't always great at bringing people together. But they also don't need to tear one another apart."

Her speech suggested she will attempt to convert her history-making vote into long-term Labour support, courting the political centre.

Ms Ardern had the chance to champion a progressive reform during the election - legalisation and regulation of cannabis, which was put to Kiwis in a referendum - but instead she deferred, choosing not to reveal her stance.

The odd position invites a comparison to one of her political idols, Julia Gillard, who was one of Australia's most progressive PMs, but one who didn't support same-sex marriage, and wore the issue like a millstone around her neck.

On election eve, Ms Ardern bit back at the similarity, saying she had backed plenty of progressive changes.

"I have supported marriage equality. I've supported and worked to get through abortion law reform. I'm supporting euthanasia," she said, also pointing to reforms to divert cannabis users out of jail.

"I call myself a pragmatic idealist," she told AAP.

"I do have aspirations for New Zealand but I'm very pragmatic about the time it will take us to get there and the road."

Part of Labour's social conservatism comes from the caucus.

That same day as Ms Ardern campaigned in the party's South Auckland heartland, three of the four Labour candidates that joined her revealed they did not support the cannabis referendum.

The diverse views of Labour's new partyroom, which is majority female, boasts a record number of LGBT MPs, Maori MPs and Pasifika MPs, will take some navigating.

Consensus-seeking, cautious and centrist: these are the watchwords by which to understand Labour's second term in New Zealand.

Australian Associated Press