In the Chat window you can Command + and Command - to make the text larger/smaller. Windows is CTRL +/-.
Unfortunately, this does not work in the Participants window and I haven't found any other settings that will affect the participants window. On a Mac there are some zooming options that can be enable, Windows has similar options, as well. It really becomes a preference at that point.
If you happen to have 2 computer monitors on your computer, you might consider configuring #1 pretty standard, but then configure the 2nd monitor to be magnified to your liking. Then when you in a Zoom meeting you could pop-out the Participants and Chat windows and drag them over to the magnified monitor #2.
