both (kinda) are already a thing.
cumflation can be achieved by having enough cum (or anything, really) filling any of the three holes a body can have (both players and inmates can be cum-inflated). From my testing, having a large penis with all breeder perks active will allow for easy cumflating
hyper pregnancy is "kinda" ingame. a specific perk in the fertility tab allows you to continuously impregnate yourself even while already pregnant, thus allowing for a large belly size.
The "Hypertus" mod allows for both of these much easier