Are you sure that PC1 = PC2 windows settings ==> font scale are same
In otherwords, in a given windows, you can set the font scaling of the PC. I don't think it adjusts graphics, just the font scale.
I believe on windows 10, you get 3 choices now 80% 100%, 125%
are you sure both instances of visio are using same units (mm vs inches)
older versions of visio picked font based on a "blind" number
so if fonts on PC1 were say Calibri, times roman, arieal…...PC2 is Calibri, areal, times roman
font = 2 would be times roman on PC1....areal on PC2
(I think later versions used font name not a blind number...so maybe a ghost).
There are tricks you can use to scale or antiscale fonts in visio (this can be handy if you have a shape that may scale significantly...and maintain readability - 10mm that grows to 100mm, might want font to scale from 10pt to 40pt automatically
Original shape is 10mm X 10mm
font could be 20pt * scale factor * width/10mm // scaling bigger shape, bigger font...scale factor can temper scaling
font could be 20pt *scale factor *10mm/width // antiscaling smaller shape, bigger font
Finally, could look at txttranform in shapesheet...might be some knobs / switches in that
(its a special section...not where the character size, spacing, bullets info called out)