Outfits and Silhouettes
For Drag Kings, an ideal masculine silhouette has long been a wide shoulder to hip ratio. This is by no means prescreptive, but it can inform how an outfit can be masculinised to feed an illusion of manhood. Shoulder pads, for this purpose, can be bought as-is at fabric stores or online and in a pinch, removable bra cups can be safety-pinned into the shoulder seam of a blazer, jersey, or coat to invent musculature.
When binding and taping, remember that men often have some breast tissue, so a completely flat chest is not required to sell the fantasy. If you are looking for a rectangular body shape whilst working with wider hips, padding your waist with a thin scarf will allow shirts to better lay upon your torso.

Men's clothes will almost always provide a more believable silhouette; they are built to create a masculine figure instead of amplifying a feminine one. Aside: womoen's clothes in King Drag. Unfortunately, men's clothes are often flavourless and simple - so don't be afraid to Drag it up. Pants are best worn on your hips - this will create quite a bit of spare room in the crotch area if you don't have the equipment to fill it, so prepare to wear longer undergarments or use cream to avoid chafing. Depending on your height, this will also pool your trousers at your ankles, so hemming them yourself or at a tailor's would not go awry. Not confident at sewing? Using hem glue will get the job done quick and easy, and can save even your civilian clothes from disuse.
For shirts with buttons, always prioritise a lack of gaping between buttons at the bust (or else only wear such shirts with ties & a tie-pin). Wearing a larger sized men's button up will sidestep the gaping, and extra length in the arms can be mitigated with arm garters - that is, thin pieces of elastic that wrap around your elbow or bicep to gather unnecessary fabric.
For blazers, a double-breasted suit jacket will invent bulk around your waist to eliminate an hourglass figure.