Yes, you can see it (I have seen Io's shadow on Jupiter and we were happy it was visitor night so that we could share the view with guests)
A 50cm mirror and 125x magnification allows you to see it when the air is not too disturbed and when you know where and when to look. Likely a somewhat smaller telescope will do, too, as light sensitivity is not too crucial - more the resolution and magnification so that you can still see the tiny black dot of the shadow. The shadow has about the same diameter as the width of some major clouds bands on Jupiter.
Stellarium is a great tool to find the right time to look at Jupiter to find these transits.
Find a local amateur observatory and they sure will be happy to share this view with you (possibly not before late northern summer due to the rise time of jupiter in 2020)