no higher va will not explode your chime as your chime will only take what is needed from the 30va.
i asked my electrician friend long ago before i changed to 16v30va if it be too much and ruin the system or have any electrical issues. he said You can’t go too high on the volt/amp(va) rating. That is just the maximum the transformer can supply. If you need less no problem.
The voltage is the critical value. If your existing system is 16 volts then you need 16 volts.
and most doorbell systems are standard 16volts
so you should be good for 16v30va as long as your existing chime or new chime is asking for 16v