While the theme park still has no firm date announced yet, Six Flags over Texas has updated its operating hours page to announce that advance reservations will be required to visit the park upon its reopening:

IMPORTANT: ALL VISITORS (INCLUDING PASS HOLDERS AND MEMBERS) WILL NEED TO MAKE ADVANCE RESERVATIONS TO VISIT ONCE WE RE-OPEN. To meet state social distancing guidelines and ensure the health and safety of our guests, all visits to the park must be pre-scheduled using our online reservation system. Check back here for details.

The Arlington, Texas theme park has been closed since March 13 due to the COVID-19 pandemic and resulting state/local guidelines.

Theme parks provide a significant challenge to try and adhere to social distancing guidelines, when thinking of things like queue lines and rides.

More information about the park’s closure and FAQs for membership/season pass details can be found here: https://www.sixflags.com/overtexas/plan-your-visit/coronavirus-update