The phrase 'sharply increase' is correct and usable in written English.
You can use it when you want to emphasize a large increase. For example, "In recent years, electricity bills have sharply increased."
This would sharply increase the government's debt.
The marketing campaign seeks to sharply increase those numbers.
He would sharply increase benefits and reduce means-testing.
A new water pollution law is under consideration that would sharply increase fines against polluters.
This approach, UPS Airlines says, would sharply increase runway capacity without laying new concrete.
Any downgrade for the UK would sharply increase the cost of servicing its huge debts.
First, the agency could sharply increase the money it receives from advertising.
The new policy is expected to sharply increase the supply of marijuana available to researchers.
But now, industry experts say, the insurers must sharply increase their premiums to avoid collapse.
If the court were to revoke his freedom, this pressure would sharply increase.
