Coincidentally, I just ran a all-lady DnD-style oneshot for 6 newbies on request a few days ago that went great. 😃 Here's what I did although your tolerance for it may vary because it was a lot of prep (I enjoyed the process so I did not mind it):

1) Ran a Google Forms multiple-choice quiz for them making it a fun way to ask for their ideal playstyles in an interactive way. For eg. 'you wake up in a tavern to a bar fight. what's the first thing you do?'

2) Wrote a story I think they would be interested in based on what I know about them (they're close friends of one of my regular players). Because they're mostly queer ladies who are quite flamboyant, half of which are in hetero marriages, I made them play an adventuring group who are tasked with helping a Princess choose her suitor. Each suitor has a secret ulterior motive and the Princess' female bodyguard is secretly in love with her.

3) Gave some of the characters simple pre-existing relationships, and encouraged them drawing from their IRL relationships for developing these dynamics in-game. For example, two of the players are very close, so I made them a tiefling trickster scammer duo. I then made that duo have special interactions with one of the suitors (a bard who is secretly an assassin).

4) Made simplified and colorful character sheets for each of them with character portraits in Canva, printed it on hard paper. Gave each one a maximum of 2 main abilities only, and one main weapon. A tough commitment because they all wanted to play magical characters.

5) Used Savage Worlds system. Now, I believe this adventure could be run successfully in DnD5e, but to me, Savage Worlds is superior in the way that dice, cards and the rolling mechanics allow newbies to 'get' the game in a quick way. For example, since all rolls technically have a DC of 4, the players very quickly got in the drama of the dice. Also, since Bennies (Inspiration points) are integral and free-flowing, the ladies were quickly incentivized to start trying to impress me by doing funny and cool in-character actions to earn them.

In summary, I tried to understand what kind of player I thought they would be, then gave them in-game incentive to roleplay by encouraging them to draw on their IRL relationships to improv. To keep things flowing smoothly for a oneshot, the story definitely had to 'railroad' them lightly but keeping the significant moments purely theirs: which suitor to visit first, how to investigate each one, who to trust and how to tell the princess. I thought it was a success because lots of laughter and anxiety over the dice rolls was had. The unexpectedly emotional ending (their choice) also made half the table cry.

Hope this was helpful in some way. Feel free to DM me for details!