embeddedservice_bootstrap.settings.language can be used for translating Salesforce Messaging for In-App and Web.

embeddedservice_bootstrap.settings.language allows us to set different languages for the Salesforce Messaging for In-App and Web.

Sample code to read URL query parameter for Language:

const params = new URLSearchParams(
    window.location.search
);
let varLang = 
    params.has( 'language' ) ?
    params.get( 'language' ) : 
    'en_US';
console.log(
    'Language is',
    varLang
);
embeddedservice_bootstrap.settings.language = varLang;

Output: