The short answer
Possibly. Some lenders may count the equity in land you already own toward the down payment or required borrower contribution.
What the lender will review
The lender will usually review the title, any existing liens, the land value, and whether the property is suitable for the loan. An appraisal may be required. Ask the lender how it treats land equity before assuming it will replace cash.
Equity is not the same as available cash
If land is already financed, start with its current loan balance rather than treating its full value as equity. The lender determines the acceptable value and how an existing loan would be handled. Land owned by a relative also needs a separate ownership review; permission to put a home there is not the same as owning the land.
Ask for two separate answers: how much land equity the lender can recognize, and how much cash you still need for closing or project expenses. That keeps an equity estimate from being mistaken for a complete cash-to-close figure.
Keep the land review separate
Write down the parcel being considered and whether it is the whole property or only part of it. Ask the lender what information it needs about that arrangement before ordering surveys or other reports. The answer should refer to your actual ownership and proposed purchase. A neighbor’s financing arrangement is not a reliable guide to how your land will be treated.