You are able to stay in Kenya for up to 72 hours with a transit eVisa if you require to leave the airport to wait for your connecting flight.
If you're not leaving the airport in a connection of fewer than 72 hours, you won't need a transit eVisa.
If you wish to stay longer than what is allowed with this eVisa, you require a different type of eVisa than a transit eVisa. Please consider a Single Entry Kenyan eVisa, which is offered through sherpa°.
If this does not suit your needs for travel, please contact your nearest Kenyan embassy or consulate for more information on how to extend your stay or for other available visa options.