Mckenna Grace Scooby-Dooby-Doo ... Daphne Needs A Clue!!!

Mckenna Grace might be a new, meddling kid in the "Scooby-Doo" legacy ... but, she's still got a love for the classic Daphnes -- including Sarah Michelle Gellar!

We caught up with the star at the airport early Wednesday morning ... and, jinkies, did she have a lot to say about her new role in the new series!

Check it out, gang ... we asked Mckenna if she's drawing inspiration from past "Scooby-Doo" movies -- animated or otherwise -- for her upcoming role in the live-action series as Daphne, and she says she's watched a large swath of the animated material out there.

She also mentions she loves the live-action movies from the early 2000s -- which star Gellar, Freddie Prinze Jr., Linda Cardellini, and Matthew Lillard -- and she's even been talking to Lillard, her "Scream 7" costar, quite a bit to gain insight into the series.

As for whether she has a message for Gellar ... Grace is quite clear she's only got a short three-word statement -- watch the clip all the way through to hear it for yourself.

The new series about The Mystery Machine crew still has plenty of mystery surrounding it ... though we do know Tanner Hagen will play Shaggy, Abby Ryder Fortson's taking on Velma, and Maxwell Jenkins will don Fred's kerchief. Paul Walter Hauser has been added to the series in an undisclosed role.

Anyhoo ... good luck, Mckenna -- you've got some seriously high heels to fill!