how do you trigger section 121 for sale of primary residence in proconnect?

In general https://accountants.intuit.com/support/en-us/help-article/form-8949/reporting-sale-home-individual-return-proconnect/L8j1M7iJI_US_en_US?uid=mndtixff

I think this is what you need

Sale of home with no depreciation or business use

1. Go to the Input Return ⮕ Income ⮕ Dispositions (Sch D, etc.).
2. Select Schedule D/4797/etc.
3. In the Quick Entry grid, enter the following fields:
   • Description of property
   • Date acquired
   • Date sold
   • Sales price
   • Cost or basis
   • Basis reported to IRS (blank=to IRS, 1=not to IRS, 2=not on 1099-B)
   • Expense of sale
   • Select the blue Details button to expand.
   • Select the three dots at the top of the screen and select Sale of Home.
   • Check the box labeled Sale of home (MANDATORY to compute exclusion).
   • Check the box labeled 2 year use test met (full exclusion).

      

     If there's no taxable gain on the sale of home, ProConnect Tax won't report the sale on the Schedule D. To force reporting on the Schedule D, scroll down to the Reduced Exclusion subsection and enter a 2 in Report on Schedule 😧 1=when applicable, 2=force [Override].