Do I need to complete Malaysia's digital arrival card before entering from Thailand, and can I buy a one-way ticket for Kuala Lumpur?

The user is planning a visa run from Thailand to Kuala Lumpur and is seeking clarification on whether they need to complete the Malaysia digital arrival card prior to their flight, as well as if they can purchase a one-way ticket since they are uncertain about their length of stay. Community comments confirm that the digital arrival card is needed and that Malaysia requires proof of exit travel, similar to Thailand's policies. Additionally, the user has already extended their stay in Thailand and now needs to activate a new E Tourist Visa after leaving.