Yes, Clonazepam is a very effective medicine for treating anxiety symptoms. It is a long acting benzodiazepine and other then controlling anxiety symptoms, it can also cause sedation.
As a psychiatrist, we often use it for managing anxiety symptoms for short duration because being a Benzodiazepine, if used for long duration ( more than 4-12 week) it can cause dependence.
It is available in various strengths like .25, .5, 1 and 2 mg.
In most cases, .25 or .5 mg is sufficient but if a patient is having severe anxiety symptoms, doses such as 1 or 2 mg might also be used by a treating doctor.
For managing chronic anxiety symptoms, SSRI antidepressants like Sertraline, Escitalopram, Fluoxetine are often the drug of choice and in such cases, benzodiazepines like Clonazepam, Lorazepam, Alprazolam can be used in combination for short duration and to be taper down slowly after few weeks.
I hope this helps, please feel free to discuss further if you have any other query.