If you’re interested in writing essays (narrative nonfiction, for example, reporting and interpreting cultural, political or historic events) or personal essays, fiction, poems, flash fiction or experimental forms, there are a number of magazines looking for such work. I highly recommend reading some of them (many may be found free online) and then writing to fit their needs, or seeing whether what you’ve written might work for them. Here are a few of the sites listing and evaluating literary magazines:
(This ranks magazines according to a number of criteria: circulation, number of writers who appear in the “Best American Series” and other factors.
A similar site: https://thejohnfox.com/best-magazines/
The Clifford Garstang site: https://cliffordgarstang.com/2019-literary-magazine-rankings/
Information about places to submit narrative nonfiction, fiction, flash fiction, poetry, and writing that fits no particular category:
https://www.newpages.com/classifieds/calls-for-submissions
https://publishedtodeath.blogspot.com/p/calls-for-submissions.html
Also useful is this list:
https://en.wikipedia.org/wiki/List_of_literary_magazines
There are various services for which one can pay, like this one: https://duotrope.com/
But I think they’re not really worth it–most of what they have you can find just by Googling around.
Most of the 4-5,000 literary magazines allow electronic submissions as well as simultaneous ones, and most submissions take place through the “submittable” platform, which tracks pieces for free: https://www.submittable.com/
A few places want emailed submissions and a very few (but some of the more prestigious journals) still insist on snail mail or have their own submission platforms. Very few (but some, like The Hudson Review and The Threepenny Review emphatically refuse to consider simultaneous submissions. They hold on to things for six months and then may say “no.” I prefer to send essays to five or ten journals at once and then withdraw them electronically if necessary.