Look for it under the Wall Paint category.
Be aware that using height-altering mods can cause "clipping" where animations like kissing or hugging may not align perfectly between Sims of different sizes. Height Chart - Mod The Sims Height Chart by Poker at Mod The Sims 4
The modder calculated that a standard Sim is approximately 187 cm tall, while wall heights are 3m (low), 4m (medium), and 5m (big). How to Use It Look for it under the Wall Paint category
Download the file from the official Mod The Sims page and place it in your Documents/Electronic Arts/The Sims 4/Mods folder. while wall heights are 3m (low)