There's also a free update:
"A Little Something for Everyone…
While the DLC expands the countryside, the core game hasn’t been forgotten. Alongside this launch, we are preparing a free update for all players that reintroduces a fan-favourite building set.
While its specific identity remains a mystery for now, keep an eye out for a set of building parts that offer a touch more prestige and architectural flair to a well-appreciated monument. We know many of you missed these more refined visuals, and we’ve finally given them the glow-up they deserve to rejoin the core Foundation experience."