I actually think stripping of titles would be the wrong action to take.
United, Chelsea, even Arsenal possibly? in the 90’s and early 00’s all bought their titles using their financial might in some capacity. But didn’t have the stringent rules in place we have too day like what City face. I think it would be hypocritical too take their titles off them but not others Clubs, who at some point didn’t exactly the same, just in a different era
I believe relegation, humongous points deductions, transfer bans etc are all exactly the way to treat them if found guilty.