Please post your version of AC, machine details, etc in your Profile (link above), as the answer to almost every question depends on this info.
Under Help > Goodies you can download the Accessories add-on and Accessories library. Select the wall(s), then invoke the add-on and select the predefined profiles for baseboard, chair rail and/or crown to be applied. Placing the accessory on its own layer lets you control its visibility.
If you have the full version of AC 10 and above (not the Start edition), then creating a Custom Profile wall offers the most reliability and power, since you can define your trim exactly as you desire. But, it will be visible in all views in 10 and 11. In 12 you can define the trim fills in the profile so that you can turn it off using the new partial structure display options.
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sonoma 14.7.1, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB