aged accounts are such a bullshit buzzword, used by account sellers to give you false senses of security. it doesn't matter specifically if an account is aged. if you have a free mw2019 account made back then, but zero activity, it's completely useless. i'd go on record and say that having an active enforcement (previous ban) on said account also is going to be a huge detriment to your "trust".
nobody knows how the system works, it's all speculation. in my experience the only thing that matters is games played without reports. now who knows how advanced this is, but COD has made it abundantly clear they're using statistics/data to make their decisions.
it's not far fetched to then believe they're comparing the amount of reports an account achieves in comparison to what their data says is "normal". i.e. you're getting 5-6 reports a game as a 6kdr player, yet the average is at 1-2 a game for others in your bracket. i'm sure its much deeper than this but you get it.
i have been toying around with a few cpp/python solutions to auto play and simulate time/losses/deaths and no reports on an account that I know has very low trust. i've yet to have the time to test if it has helped, but plan to soon.
long story short, leave the 2019 account with an enforcement alone. i'd argue a 1-2 month account with no enforcements, a solid KDR/accuracy/low headshot/etc without reports will be much better. so make an account and as lame as it sounds, use just visible ESP/super low aimbot (if not none at all) for a period of time and get your score up. i find buying the game helps a lot too. stay away from hardcore, those paranoid mfs spam report anyone for anything.