She posted a long policy statement/vision on Medium
Two things that stand out [to me], which haven't been emphasized in the other answers:
unlike Trump, while I think tariffs are an important tool, they are not by themselves a long-term solution to our failed trade agenda and must be part of a broader strategy that this Administration clearly lacks. [...]
If we raise the world’s standards to our level and American workers have the chance to compete fairly, they will thrive — and millions of people around the world will be better off too. [...]
Under WTO rules, a country designated as a “non-market economy” can face more serious trade penalties. I will push for a new “non-sustainable economy” designation that would allow us to impose tougher penalties on countries with systematically poor labor and environmental practices. We cannot allow countries that treat their workers and the environment poorly to undercut American producers that do things the right way.
She generally wants to involve environmental groups more in the US trade policy, including giving them a seat at the table in bilateral negotiations, on top of the WTO-based approach. She even slams Obama for not doing that:
Environmentalists do want a seat at the table, but it matters which table, and whether they’ll be treated as equal partners in the room. Sierra Club trade program director Ben Beachy pointed out that during negotiations on the Trans-Pacific Partnership, or TPP (formed by Obama but scrapped by President Trump), the energy committee had representatives from Chevron, Haliburton, and the National Mining Association, but not one environmentalist.
But more notably she supports a concrete way to force other countries to comply:
I will push to secure a multilateral agreement to protect domestic green policies like subsidies for green products and preferential treatment for environmentally sustainable energy production from WTO challenges. And because big corporations will move their production to the countries with the weakest greenhouse gas emissions standards — undermining global efforts to address climate change and penalizing countries that are doing their part — I will impose a border carbon adjustment so imported goods that these firms make using carbon-intensive processes are charged a fee to equalize the costs borne by companies playing by the rules.
There's nothing quantitative in her policy vision, but then Trump was also non-specific in that (quantitative) respect before he won the election, if I'm not mistaken.
It's also noteworthy what she isn't mentioning as an explicit problem, namely the bilateral trade deficit with China or with other specific countries, Germany in particular. While Trump's complaint about the deficit with China can be attributed in no small part to to lax environmental and labor policies in China (although Trump seems to prefer to slam them on IP theft/unfairness), so it's probably easy to guess that Warren won't be exactly happy with China either, it's harder to see how one can attribute the US trade deficit with Germany (for example) to environmental or labor conditions over there. I'm not saying Germany would be off the hook in Warren's approach, but it's less obvious how (trade with) Germany could would be penalized under her vision.
She also makes no mention (at least in that statement) of using national security considerations a key part of the trade policy. For those who don't know, Trump's administration has even produced a section 232 document on cars this spring, although no tariffs have been raised using that yet (unlike the section 232 decision on steel and aluminium); the tariff decision for cars has been postponed for 180 days. The official 232 document on cars says for example
The United States defense industrial base depends on the American-owned automotive sector for the development of technologies that are essential to maintaining our military superiority.
