Change return type based on value of parameters

function doSomething({user, includePfp}){
if(includePfp) return {...user, pfp: 'wow'}
return user
}

doSomething({user}) // returns type of User
doSomething({user, includePfp: true}) // returns type of User & {pfp: string}

function doSomething({user, includePfp}){
if(includePfp) return {...user, pfp: 'wow'}
return user
}

doSomething({user}) // returns type of User
doSomething({user, includePfp: true}) // returns type of User & {pfp: string}