If the property was an investment, you can deduct the loss.  If the property was personal use, such as a second home, or you let a family member live there, then it is personal property and you cannot take the loss.

Further question: I purchased land in 2002 and sold it, at a loss in 2020. What do I need to submit to claim this loss?

Yes, if this land that was sold was just plain land and was never used for farming or income-producing or as business property, you would report the sale on Form 8949 carrying to Schedule D using the correct adjusted basis and sellng price and if it was just unused land, then it would end up showing on Sch D as a capital gain or loss.