The golden barrel cactus or echinocactus grusonii will over time turn into a large 'ball' or barrel shaped cactus I have seen them a big as 3 feet tall and over 4 feet wide, but those are very old. AFAIK this cactus is almost or mostly extinct in nature the habitat area was destroyed by the formation of a large reservoir, it of course one of the most commonly cultivated cacti. A secondary population has relatively recent been discovered but it occurs a huge distance away from the original rather restricted area where this plant occurs and those plants show enough variation from regular E. grusonii that that population might be considered distinct.
Like most cacti it does not like wet feet - ie. it wants well draining soil and while it can take regular watering the soil needs to dry out quickly and completely between waterings. It requires bright light, it grows in full sun here in the low Arizona desert so especially in winter you might struggle to provide it with enough light, but having it under a good light source will definitely help. In the summer you might be able to grow it outside in the full sun, as long as the soil does not get waterlogged frequently from rain, it will probably be fine. Given its eventual mature size, with time this plant might become really difficult to move, so keep that in mind.
The Old Man of the Andes which the common name most often used for Oreocereus celsianus. In its native environment it grows in the high Andes mountains, so it is very frost resistant and does not deal extremely well with low desert heat - I have mine receiving only about 4 hours of sun a day in the summer and despite its hairs it still ends up looking a little toasty during the height of summer. While frost resistant, wet cold is just as deadly to it as hot and wet. So again provide well draining soil water infrequently when the soil is absolutely dry. With time these should become very tall (10 ft) columnar cactus. For me this is a slow grower so it should be fine in a pot for a long time. Again it needs lots of bright light to grow true, so provide as much light throughout the year as you can.
I hope this helps. Good luck!
