How do I know if I can tune strings up?

So, I am looking at someone’s kmise baritone, they have never used it, the info that comes w it says it is supposed to tuned gcea. It is currently untuned but centered around dgbe, and I am nervous to tighten it more but it doesn’t sound amazing and I think it could have more volume in the higher tuning, just nervous...

Right, the material that came with this says it has gcea strings on it, and I know these instruments are often shipped de-tuned, so not sure if I should proceed with the uptuning or not...

If it sounds good and has an ok tension at DGBE, there is no way those same strings are going up to GCEA. Ignore the "supposed to" comment. Tune it however you want to tune it - as long as you start with strings designed for your desired tuning.

I'm surprised nobody has mentioned this yet.

Are the strings all plain? Or is there a wound 4th and 3rd?

If there are two wound strings, you can bet it's a DGBE set.