The 124cc 4-stroke DRZ is a popular dirt bike choice, known for its versatility and reliability. In terms of your height and weight, it should generally be suitable for you. However, it's important to consider a few factors:
Height: Being 5'11" (180 cm) tall, you may find the bike to be slightly smaller than ideal. The DRZ has a relatively low seat height, which can make it more manageable for riders of varying heights, but it may feel a bit compact for taller riders. It's recommended to sit on the bike and test it out to see if you feel comfortable and have adequate legroom.
Weight: Weighing 70 kg (154 lbs), you are within a reasonable range for the bike. The DRZ 124cc engine should provide sufficient power for your weight, especially for trail riding and casual off-road use. However, if you plan to do more aggressive motocross or off-road racing, you might consider a more powerful dirt bike option.
Ultimately, the suitability of the bike depends on your riding style, preferences, and the specific terrain you'll be riding on. If possible, it's always a good idea to test ride the bike or consult with experienced riders to get their insights and recommendations based on your needs.