How to create site collection programmatically in SharePoint 2013 using csom c#?

Question

Tried looking for it all over the internet but no success, I can only find the one for Sharepoint online.

How do you create a Site Collection on-prem using csom c#?

Answer 1

You can give this a try;

private string CreateSiteCollection(string hostWebUrl, string url, string template, string title, string adminAccount)
{
    // Resolve root site collection URL from host web. We assume that this has been set as the "TenantAdminSite"
    string rootSiteUrl = hostWebUrl.Substring(0, 8 + hostWebUrl.Substring(8).IndexOf("/"));

    //Resolve URL for the new site collection
    var webUrl = string.Format("{0}/sites/{1}", rootSiteUrl, url);

    // Notice that this assumes that AdministrationSiteType as been set as TenantAdministration for root site collection
    // If this tenant admin URI is pointing to site collection whihc is host named site collection, code does create host named site collection as well
    var tenantAdminUri = new Uri(rootSiteUrl);
    string realm = TokenHelper.GetRealmFromTargetUrl(tenantAdminUri);
    var token = TokenHelper.GetAppOnlyAccessToken(TokenHelper.SharePointPrincipal, tenantAdminUri.Authority, realm).AccessToken;
    using (var adminContext = TokenHelper.GetClientContextWithAccessToken(tenantAdminUri.ToString(), token))
    {
        var tenant = new Tenant(adminContext);
        var properties = new SiteCreationProperties()
        {
            Url = webUrl,
            Owner = adminAccount,
            Title = title,
            Template = template
        };

        //start the SPO operation to create the site
        SpoOperation op = tenant.CreateSite(properties);
        adminContext.Load(op, i => i.IsComplete);
        adminContext.ExecuteQuery();
    }
    return webUrl;
}

Taken from; Provisioning site collections using SP App model in on-premises with just CSOM