Home appraisals are subjective
Lenders will require an appraisal for most home purchases, and they won’t loan more than the amount of the appraisal.
Unfortunately, home appraisals are subjective. 3 different appraisers could come up with 3 very different appraisals for the same home.
BEFORE you make an offer on a home, make sure your realtor performs a comparative market analysis of recently sold comparable homes. Have them show it to you and review it with you.
A realtor will not be able to guarantee that your home will appraise for what you offer, but they could give you a better feel for the overall risks.
This will mitigate the chance that you will make an offer on a home that is more than the appraised amount.