Is it possible to automate Solver in a macro in Google Sheets? By that I mean setting and changing the Solver parameters within a macro. I am able to do this in Excel but I can't find a way in Google Sheets.
Short answer: No because Google Sheets hasn't a built-in Solver feature and because macros can't be used to automate features added by add-on.
As an Excel user that knows about Excel's macros that is new to Google Sheets, the first thing that you should have in mind is that there are a lot of Excel features that are not available in Google Sheets, the second thing is that Excel's macros and Sheets' macros are very different, i.e. the programming language isn't the same, Sheets macros only run online, among other differences.