You'd also have to consider his social circle. Does he have a local younger sister or local similarly aged female cousins to help him out with introductions? I've known guys with girlfriends who would have been incel/borderline incel without sister introductions. Could he do a weak social circle option and join a co-ed sports league?
Should almost change the Title of Sosuave to: “Forget working on yourself and making money and dressing well and working out for girls in the early 30s. Just get a hot sister when you are 16 and you will be set.”
For a man, having a younger sister living in the same geographical area is one of the biggest game advantages that exists.
She doesn't even have to be hot. If she's not overweight and has decent facial aesthetics, she'll have good enough friends for introductions.
This will drastically cut down on the amount of time spent sending DMs on social media, approaching strangers in any venue, or spending time swiping and texting.
A younger sister is not a substitute for self-improvement. A guy needs to have some level of physical attractiveness and decent job. I would estimate that a local younger sister in her 20s/early 30s and childless is worth somewhere between 1-2 points on the SMV looks scale and about $50,000 - $70,000 worth of annual salary. In other words, if a man doesn't have a local sister, he would need to improve his looks 1-2 points through diet/lifestyle and up his salary $50,000 - $70,000 to get the same results cold approaching or using tech-based date arranging methods as having a younger sister that can provide introductions.
A good relationship with a local female cousin can provide the same advantages to a lesser degree.
The value of a local younger sister decreases once she gets married and/or has kids and her female social circle goes through the same thing. However, there's still even a decent chance 45 year old guy with a 40 year old sister might still be able to get some introductions that would save him time approaching or swiping.
I've not heard of men with local older sisters gaining any sort of meaningful advantage. Depending on the age difference, an older sister might have some social connections that are meaningful. It would have to be a narrow age difference between the brother and sister, no more than 3 years and likely less than 2 years. At best, a sister 18-24 months older might be able to get her younger brother a girlfriend who is 1-2 years younger.
Non-local sisters do not provide much in the way of meaningful game advantages. Men with non-local sisters will have to put in time either building local social circles, approaching strangers, or using the tech-based methods. The only possible advantage of a non-local sister is first hand observational insight and some experience interacting with women earlier in life if the age difference in somewhat narrow.