Trading top 10 QBs in the prime of their careers isn't common, so forgive me but I'm just listing "comps" up to you for definition...
33 age season Matt Stafford traded to Rams for 2 1st round picks + 3rd + 2nd contract age 27 Jared Goff
26 year old Jay Cutler traded to Bears for 2 1st round picks + 3rd + age 27 Kyle Orton
27 year old Deshaun Watson to Browns for 3 1st round picks + 3 mid to late round picks
34 year old Russell Wilson traded to Broncos for 2 1st round picks 2 2nd round picks + Noah Fant TE and Drew Lock
After reviewing this, the Vikings likely have to offer 3 1st round picks, a 2nd or 3rd (maybe multiple), McCarthy, and maybe 1 more player (Oliver, Redmond, etc?)