Filming for Megalopolis: backstage scenes
The information is based on the call(s) for extras. Grace may not necessarily have been involved in the shoot on all of these days, and she will have been shooting on other days as well, doing scenes where no fans were involved. There is no Grace-related media for this event at the time of writing (the day after the event).
However, footage taken by bystanders of filming outside a theatre shows posters in the background for a concert by "Vesta Sweetwater" - the name of Grace's character. Whether she is performing at the event guests are arriving for (a wedding reception for the mayor or someone in his family), or just a poster for some other event, time will have to tell. The posters are visible at the left side of the frame at 1:36 in the video (where just the name VESTA is legible). A still shown later in the video shows the lower part of the poster with the name "Sweetwater".