As described in sec::modules, each module has a settings template parameter.

Dynamic settings

These settings are considered at compile time. For certain purposes, it is unhandy to recompile SMT-RAT for every parameter. For this, module parameters can be set

via the command line using --module.parameter key1=value1 --module.parameter key2=value2 ... or
via the set-option command of SMT-LIB: (set-option :key "value").

These parameters can be accessed (most appropriately in a settings object of a module) via int my_setting = settings_module().get("my_module.my_setting", 2) or std::string my_setting = settings_module().get("my_module.my_setting", "default_value"). Note that the second parameter is the default value also specifying the type of the setting to which it is parsed.