The KTM 640 Adventure is a relatively tall motorcycle with a seat height of around 36 inches (91 cm). As a rider who is 5'5" (165 cm) tall, it might be challenging for you to ride the KTM 640 Adventure comfortably due to its height.
Factors like your inseam length, leg strength, and overall riding experience can also influence your ability to handle taller bikes. Some riders with a shorter stature can manage taller motorcycles by using techniques such as sliding off the seat slightly when stopped or using one foot to balance the bike while keeping the other foot on the footpeg.
It is recommended that you visit a KTM dealership or a motorcycle shop and actually sit on the KTM 640 Adventure to see if you can comfortably reach the ground with both feet while seated on the bike. Additionally, consider consulting with experienced riders or motorcycle instructors who can provide you with valuable insights and suggestions based on their expertise.