The value of the estate would not be impacted greatly by what you propose. The money raised on the mortgage would be offset by the amount you had in savings that you didn't use for the purchase.
E.g.
Estate worth �700,000
Buy a house for �200,000 with a �100,000 mortgage.
Savings and investments = �600,000
Buy a house outright for �200,000
Savings and investments = �500,000
In both cases the value of your estate is the same give or take a little for servicing the debt and interest/returns on savings.