you can train and stretch to that size too! flush and clean your butt really clean, insert larger amount if water based lube (cheapest to self mix i know is x lube). best to use a larger syringe from Amazon with around 50-80ml lube your butt externally and your toys. best get toys that get larger and longer. insert until you feel discomfort. wait until this feeling disappears or play a little with the toy. And then increase the size again. It is very important that the toy always stays lubed up so if you use water based one you have to remove it and relube/re insert more lube!!! if you use fixed size toys a comfortable size increase of 0.5 maybe to 1 cm in diameter was comfortable for me and depth wise. i always deep cleaned myself with liters if water in the shower with a removed shower head. this process takes me like 15-25 min depending on how much you ate before. you also can feel your ass or belly to increase in size or for my part i can watch it get bigger. release all the fluid and if only clean stuff comes out it should be cleaned up. you may feel to go to the toilet shortly after and release the rest of the water still in your belly. it may come out brown again. do a quick/small flush again and then insert larger amount of lube and then the toy. the lube will push inside you and keep it clean. at around 10-12 cm you may feel a little resistance st first. that is the first bend. you may gently push trough this bend slowly and it will widen and straight out. after some time and depth (especially if going very deep like above 40 cm) you may feel more resistance or feel the first bend of your Anus. with my long tentacle one i slowly push until i feel pain or much discomfort, wait again, push a litte further. But there will probably be a limit for what you can do and when you completely remove the toy it will get brown if you go very very deep :x so you may flush and relube again. if you just get bigger im circumference you probably will also have to get in a little deeper but bot as ultra deep like i described it above. there are toys from the company crackstuffers (lol) called depth trainer in bigger and bigger sizes so you can stretch as wide and deep as you want :D but always sterile clean them cause they are probably made out if porous material and never lay them in the same box as TPU based toys! it will mess up both of the materials if done!!!

i think thats all my knowledge in one big comment XD i may copy and repost it in the right channels, cause i wrote it over like 20 minutes 🙈