Cornice molding under BEVEL modifier

I found this feature but can’t get it to apply onto my simple plane mesh. Anyone know how to do this.

In 2.83…I never subdivided as you are using Vetex Only…selecting all down the loop tried to add a profile to every one of them…
I just grabbed the 2.91 Update and haven’t unzipped it yet…in the meantime perhaps someone else will answer you before I get to add it back in…
this is 2.83 LTS…