How Does large companies onboard employees globally?

I am trying to understand how big companies handle global hiring and onboarding.

If a company hires people in multiple countries, how do they manage things like contracts, payroll, compliance, and local laws? Do they use one system for everything or different vendors in each country?

Also, how do they handle onboarding experience for remote employees? Is it standardized or localized?

I am especially curious about:

• Tools or platforms they use
• How they stay compliant with different labor laws

Would love to hear real examples or experiences from people who have worked in global teams or HR roles.