PUMAUnisex's Popcat 20 Slide Sandal

I am awaiting a refund on a product that was returned 3 weeks ago

My wife is size 6. Do i need to go up a size?

Can you wear them indoors ?

Does anyone know if they stretch any across the band? A bit tight but not sure if they will stretch with wear? Needed for holiday going in 2 days 😲