[NutmegCarrera]

You want to humidify.
If you are able to keep them in one room - a room humidifier and a digital humidity gage are the way to go.
Keep it around 50%.
(My daughter keeps hers acclimated by hanging on an INTERIOR wall and regulates the humidity manually.)
This is important for acoustic and hollow body guitars.
I think solid body electrics- they’re pretty stable.

When keeping in the case - she uses an inside-the-sound hole humidifier pack.
They are available and can be “recharged” when their humidity level is ‘used up’.
There are hygrometers available for inside the case. Both the ‘litmus test’ type - as well as a digital or analog gauge.