How to Playtest One D&D and More
First, you should know One D&D will be fully compatible with D&D Fifth Edition, so if you have a pile of physical sourcebooks sitting in your RPG library, or end up preferring 5E to the continuing adjustments made to the game through One D&D, you and your hapless party of adventurers will not be wiped out of existence, just eaten by an owlbear.
But if you’re excited about One D&D, you can head over to Wizards of the Coast right this minute and sign up for the Unearthed Arcana playtest materials here. New playtesting content should be dropping monthly, and the playtests themselves will be running through 2023, which means the new One D&D core rulebooks won’t be available until 2024.
One thing you can expect to be a major part of One D&D is the game’s focus on diversity in all sorts of manners, which began in the sourcebook Tasha’s Cauldron of Everything. The character creation in Unearthed Arcana playtest no longer ties Ability Score bonuses to race, but now links them to Backgrounds, i.e., where your character has lived prior to the adventure you’re beginning. Custom Backgrounds will even be able to be made, at least for now. Basically, this adds for more versatile and individualized character creation and, thus, storytelling.