According to a report from Android Police, an update is rolling out to fix an issue that prevents users from unlocked the bootloader and performing mod. The change is included in the first update of the phone.
A bootloader is a piece of software that is used to load the operating system onto a device. Gaining access to the bootloader can give you full control over your operating system. It allows you to modify the look and feel of the phone. Some phone-makers and carriers don't allow you to change the settings on your device. It allows you to look at devices that aren't tied to a specific carrier.
Several users of the Pixel 6A were disappointed to discover that they couldn't access the bootloader, and later confirmed the issue on their own review unit. A fix is included in the latest version of the phone, but it doesn't mention it in the patch notes.
Depending on carrier networks, the update will roll out over the next week. You shouldn't have to wait too long if you've been looking for a way to modify your new phone.