Can I plug 2 guitars into a Focusrite Scarlett Solo, i.e. 1 into the regular instrument input and another using a converter to XLR like: MainCore-6 35mm-Socket-Adapter-Converter
Is it possible and safe? Is it dangerous to accidently use the 48v switch.
Let's just stay safe & say 'no'.
Not only will the impedance be wrong & your guitar's output far too hot for a mic channel, sending phantom down the line to anything other than a mic can break things.
You could unbalance the cable by bridging cold to ground, but you're still facing the mismatch. It's not a cable I'd be happy to have floating round the studio, tbh.
