UCLA Majors

I really like engineering- mostly chemE and MSE. I know the curriculum is hard, so I will work hard to try to get internships and all that. Regarding job prospects, I wasn’t sure about MSE as it isn’t a common engineering major/field.
However, the reason I am even mentioning engineering is because it is a sort of backup for me.
I REALLY want to be a doctor. However, it seems that majoring in bio or something will be useful for med school, but only like 10% of starting premeds end up their. I will try my best, but if I major in bio or something related, I am worried that there is a chance I won’t get in.
If I majored in bio or biochem first, and I don’t like premed, is it possible to switch into an engineering major later?