Can I tie into a double 30 amp dedicated circuit outlet with 12-2 and 4 20 amp outlets in the garage the only thing on this circuit is a 5 amp freezer?

Not a chance!

First, unless that freezer requires 30 amp, get it off that circuit and onto a 20 amp circuit.

The way to do this would be to set up a 30 amp sub-panel that then run the needed 20 amp branch circuits from the sub-panel.

If you do what you want to do, please update your will and put me down as a beneficiary and then put your fire department on notice that you will be needing them soon! :)

I agree. Absolutely NOT!
Also, a small freezer should NOT be on a 30A circuit. If you have general use 15 or 20 amp receptacles on this circuit it is a pretty serious code violation. They should only be on a 15 or 20 amp circuit.