I'm creating a Node.JS/JSForce/Express API to create external identity users in SF, but I don't want the user to receive the welcome email for the Experience Site they're enrolled in, although users added via SFDC should. My Typescript code looks like this:

   // Single User record creation
    const userObj : {[key: string]: string}= {};
    // these are the required fields
    userObj['ContactId'] = objRecordData["ContactId"];
    userObj['FirstName'] = objRecordData['FirstName'];
    userObj['LastName'] = objRecordData['LastName'];
    userObj['Alias'] = (objRecordData['FirstName'][0] + objRecordData['LastName']).substring(0,8); // max 8 chars
    userObj['Email'] = objRecordData['Email'];
    userObj['Username'] = objRecordData['Email'];
    userObj['FederationIdentifier'] = objRecordData['Email'];
    userObj['ProfileId'] = await getProfileId("External Identity");
    userObj['EmailEncodingKey'] = 'ISO-8859-1';
    userObj['LanguageLocaleKey'] = 'en_US';
    userObj['LocaleSidKey'] = 'en_GB';
    userObj['TimeZoneSidKey'] = 'Europe/London';
    userObj['IsActive'] = "true";
    await jsforce_conn.sobject("User").create(userObj,
        function(err, ret) {
            if (err || !ret.success) {
                logger.error("create SF User failed: " + JSON.stringify(userObj));
            } else {
                logger.info("Created User record " + ret.id + " for " + userObj['Email']);
                objRecordData['UserId'] = ret.id;
            }
        }
    );

It looks like this is possible via Apex code using the method Site.createPortalUser(user, accountId, password, sendEmailConfirmation) : see https://developer.salesforce.com/forums/?id=9060G000000IA5FQAW

Can it be done? There is a reference to calling Apex code from an LWC, but it's beyond my comprehension currently : https://developer.salesforce.com/docs/component-library/documentation/en/lwc/lwc.apex_call_imperative