I haven't really looked into Warren's foreign policy.
I assume she'll choose a professional and competent team, shore up alliances that have been frayed during the Trump Admin, not act erratically, rejoin international agreements (on climate, Iran, etc), and avoid warmongering.
If it's sort of a stable bland Obama-ish policy that'd be fine and a great improvement. Hillary was always too hawkish for my taste. I think Warren would be wary of foreign interventions a la Obama. Trump is wary of foreign wars but had Bolton and other Iran warmongers on board, and has really pushed Iran into a corner where its felt compelled to lash out. Trump also has allowed the Saudis free reign to kill and maim poor Yemenis. And the Syria debacle in which we greenlighted war crimes and endangered a good ally, and had to scurry out in the face of Turkish shelling and Kurdish curses. Pressuring the Sauds to stop their illegal, nasty war in Yemen would be a great start. Reining in Israel's rightwingers would be a good second effort.
I expect Warren would have a tough policy towards China -- hopefully including human rights -- without all the lurching erraticism that Trump has deployed. I expect Warren would be a supporter of Ukraine and a detractor of Russia.
Trump has really set the bar low and made a mess of so many situations, that it won't be hard to look like a foreign policy guru after him.
This election and especially for Warren is about domestic policies and getting the US back on its feet. And getting gov't back to running professionally and competently and for the benefit of the many not just the elite.
Certainly I'd trust Warren to run foreign policy more than Trump and Bolton and a bunch of rotating generals and Trumps crazed personal attorney.
But yeah, I'll look into Warren's foreign policy when I have time.