Kenya is a visa-required country
Many nationalities could get a visa on arrival before the COVID-19 pandemic, but now a visa in advance may be required. Check out Kenya's official visa website and give yourself plenty of time to finish the application. Even after submitting and paying, random checks can result in additional questions for some travelers.
You need to make your visa application at least 30 days before your trip. The application is detailed and accessible online. For example, all of your lodgings require addresses, phone numbers, and websites. A travel itinerary, proof of a return air ticket, and a recent color photograph are also required. Kenyan visas are valid for three months after they are issued. Even for domestic flights between Nairobi and Mombasa, print a color copy (or two) of the visa and payment once it's been issued. Don't forget to check the current entry requirements for information on COVID-19 test results, health status, and vaccination records.