In the Encase basic theme, the logo resized nicely. In the Pro theme, there is less functionality. In either case, there are no guidelines that I can find that suggest the right logo size.
Here’s the link to the Support topic
There are no dimensions listed there, it simply says this:
How to Set up Your Logo
With Encase Pro, you get several logo and title options to choose from:
Go to Appearance->Customize->Site Title & Taglines->Site Identity and choose your logo.
Please keep your logo to a reasonable size because there is only so much room to put one in when your site menu is using the Primary Menu location (positioned to the right of the logo container). You get more flexibility if your site title and logo are one image, but for a logo with a text based title and tagline (like the demo site), your logo should be close to the size you see. If you need a bigger logo area, then you will need to put your main menu into the Secondary Menu location (below the logo).