dnd 5e – Things that accumulate with the improved criticism of the champion?

In the PHB p. 72 only says:

Improved critic

Beginning when you choose this archetype in the 3rd.
level, your attacks with weapons make a critical hit in a
Roll of 19 or 20.

So my guess is that in the attacks made by Booming Blade or Divine Smite, the critic still applies to the effects of the normal attack, but does the critical strike have an effect with the Booming Blade on the impact of the Thunder or the Smite Radiant? ? What happens with the bonus action scripts? As Thunderous Smite, does that affect them too?

Basically, my main question is, does the Critical Improvement basically increase your critical range, or does it specifically only improve the criticism of the regular weapon attacks of the attack action?