There is a wide variety out there. I'd recommend Googling some synagogues that you might visit post-pandemic, and often there are photos there of its members. That should give you some sense. If you can arrange a socially-distanced outdoors chat with a woman in a prospective community, that could be incredibly helpful.
As Alex commented, there's a wide variety included in "Modern Orthodox." One dating site actually has categories such as "Modern Orthodox - liberal" and "Modern Orthodox - machmir [stricter]." Something to think about is what aspects of Judaism are speaking to you, and making Conservative feel like it's not the right fit. Finding a good fit with a community makes all the difference.
Very roughly speaking, you would at least see this:
At synagogue:
- Skirt or dress covering the knees
- Sleeves at least covering the shoulders
- Some sort of hat or other hair covering, for married women. (There are virtually no mainstream Orthodox communities in the US that expect never-yet-married women to cover their hair, in fact it would seem out of place. Widows and divorcees are a gray zone.)
At home or the office, the more liberal side of Modern Orthodox would be comfortable with pants and no hair covering. (I think bare shoulders is still unusual.)
(Those two right there -- pants and hair covering -- are actually commonly seen as questions in the Orthodox world when dating! There are women who say no way am I going to cover my hair, and there are guys who will say no way I'm marrying a lady who fails to cover her hair. Or the reverse! There are also people who are more flexible.)
Moving towards more traditionalism, you'd see at least some hair covering (at least outside the house), to "as long as no more than 3 inches of hair are visible", up to full hair covering [hat, scarf, or wig]; sleeves past the elbow; and always a skirt or dress [not pants, barring a job physically requiring it like nursing] to nearly the ankles. (At this end of the spectrum, "modern" isn't about a lenient reading of modesty guidelines, but about a broader view of engagement with the outside world.)
For a sense on this more right-wing side of Modern Orthodox (or "Modern Orthodox machmir"), the back row in this picture is a graduating class of women who are trained as "advisors on halacha" -- not aiming for a title like "rabbi." Hair coverings (all these women are married) seen here are: wigs, wigs-with-hairbands, cover-it-all hats, and hats/scarves with a small stripe of hair visible. All these women attended the same seminary, with a curriculum developed by Rabbi and Rabbanit Henkin -- more on the former below.
All of the above comes down basically to interpreting various statements in the Talmud, surprise surprise. Rabbi Yehuda Herzl Henkin's book on Tzniut (modesty) goes through all of these in depth and is recommended, if you have the patience to go through a whole lot of nitty-gritty source material. (Rabbi Falk's book on Tzniut reflects a very right-wing ultra-Orthodox approach; unless that's what you want, please avoid it. Rabbi Henkin rejects it becauseRabbi Falk's approach, which he feels can lead to we are so afraid of women standing out that we can't let them be outstanding.)
Good luck with your spiritual journey, especially during these trying times.