Benzodiazepines can lower respiratory rate, yes. If you're having difficulty breathing, not making it harder would be the smart course. If this is something you take regularly, maybe take half (and maybe consult your doc first).
If you don't already take drugs from this class, as someone who has dealt with benzo withdrawals, I'd say "please don't start." Meditation and a hot bath, and listening to relaxing music are good ways to deal with anxiety w/o substances. Herbal tea and sleep are both good for anxiety (and fluids and rest are important during covid). CBD and melatonin also. NyQuil might be a better choice. Hell, I'd even suggest cannabis over benzos, but that's a whole separate thread (and may not be legal/accessible where you are).