Worldbuilding means deciding on a type of style. In the case of an antique society, one must be restricted to what is possible and what is not. In the case of my Shadow series, a British Isles reverted back to the Dark Ages and not in touch with other countries will not have access to silk or cotton. Equally obviously the artificial textiles will not be available, either. What is left? Leather of sheep, cow, goat and pig. Wool and flax. So yes, a person can have linen and fine wool garments. Yes, they can have leather garments and shoes, but these must be made without industrial power, as in the old days. Curing leather is exceptionally unpleasant and involves the use of ammonia, (stale urine).
Linen? It is very, very labor intensive and people would have had a care to look after their clothes. Things would be darned and patched. Here is how to make linen out of flax the old way.