What it is
Tone is the volume and heat of an ask: how forcefully, coldly or finally you say it. Standard is where the line actually sits and whether it moves. Harshness turns the tone dial. Permissiveness turns the standard dial.
The two are independent. The fear of “going soft” only applies to the standard. You can lower your tone all the way and keep the line exactly where it was.
How it shows up for me
For years I thought being firm meant being loud. Separating the dials changed my parenting: same rules, quieter voice, fewer tears on both sides.