How about two variants:

.config(timeout = …, enabled = …)

and also

.config(config: TestConfigBuilder.() -> Unit

so that the first one can delegate to the second one

And then you can share configs by doing

val config: TestConfigBuilder.() -> Unit = configBuilder { … }

I guess I’m mostly advocating for the current postfix function-style. But be aware I don’t use configs often so I might biased. The last version rubs me the wrong way somehow. Something about adding a global method that’s not spec-specific.