You cannot "print" Tslips from a tax return. But, you can do screenshots and paste them in a document for the CRA.

When on the screen you want to print - hit the "PrtSc" key on your keyboard and paste it to a document.

Also, you can sign into your MyAccount (link below) with CRA to access them on last years tax return and do print screens from there as well.

https://www.canada.ca/en/revenue-agency/services/e-services/cra-login-services.html