Hello ASF, thanks for reaching out to the Community
We appreciate how handy it would be to have the option for multi-year comparison reports in QuickBooks Online.
So that this can be considered, please use the feedback tool in QBO (click the Cog > Feedback) or pop your idea over on our recently launched QuickBooks Idea Exchange board. We'll be reviewing all ideas submitted here, and if it gets to over 50 votes, we will review it with our Product team.