Charges were dropped in July 2020 and I filed for citizenship in December 2020.
Since the charges were dropped (that is, assuming they were fully dismissed), and that happened before you applied for citizenship, they will have NO impact on your eligibility for citizenship.Should I hire a lawyer now and send a letter of explanation to ircc or will they follow their process regardless?
As I previously noted:
Fingerprint requests, and sometimes a request for copies of the official court records to verify the outcome of the charges, is typical. This is of course non-routine processing and can cause some delay in being scheduled to take the oath. But again, where the charges were totally dismissed (dropped), they will not affect your eligibility for citizenship. It just might take a little longer.
Having law enforcement destroy fingerprints and photographs will NOT change this. That mostly affects public access to information about the charges.
Other than provide the finger prints in response to IRCC's request, there really is nothing else you need to do . . . except wait to see if you get a request for copies of the official disposition in the court records.
Other than that bit of non-routine processing to verify the outcome of the case, this is NOT a problem for your citizenship application.