That sounds nice big cage, but as you’ll have found, I expect, even with only two the problem is keeping the cage clean and dry. Young chicks are at high risk of coccidiosis whilst still under a heat lamp, which is usually fatal, so cleanliness and dry conditions are essential. You’ll have discovered how strongly their poo smells, since unlike chicken chicks the blobs are so small and soft that poo picking isn’t really possible, so they tend to walk in it and spread it around. If it comes into contact with damp litter in the warm conditions it can easily cause bacterial problems. Thry peck around in the bedding and could ingest the coccidiosis oocytes. If you put in too much by way of decoration it becomes harder to clean up and change the bedding when needed. What sort of drinker do you use? The best kind is the ones with a reservoir that clips on to the cage mesh and has a lip that comes through into the cage at chest height for the birds, so they don’t paddle in it or pollute it by pooing in it, as they would do with an open shallow dish.
Reduce the heat gradually if possible, ie if you have a lamp suspended over the cage you can raise it a bit each day. They will tell you what they need - if they huddle together under the lamp and are reluctant to come out to run around and feed they’re too cold, but they do need to be able to get away from the heat source if they’re too hot. Temperature may drop at night, even indoors, so use a cage thermometer to keep an eye on what it’s getting down to. They should be well enough feathered by 6 weeks to be off heat, but might like a bit of warmth overnight if the winter is very cold. With more birds they could huddle together to keep warm.
There’s a sort of lamp called a dull emitter which is good for chicks as it only emits heat, not light, so when left on overnight they do experience ‘night’ as well as day abd have a proper natural rest in the darkness. Or there are chick warmers like the Ecoglow which are basically infra-red heated plates that the chicks can get under, like if they had a real Mum.