Can childcare be difficult?

I am a young boy, I have a chance to earn money during the holidays as a babysitter. I will look after an 11 year old boy. but the problem is this.
I am about 4'7 (1.40 m) and 67 pounds (32 kg).
and I am afraid that the child may dominate me
What do you think?
Can childcare be difficult?
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