4 year old's pee smells very strong and looks cloudy...

I was looking after a family member's kid and when they went potty after school, their pee smelled very strong and to me looked a bit cloudy. They're 4.5 years old and have some issues including a very rare genetic condition and suspected autism, hence why they are a bit late with a number of developmental stages including potty training, toilet etc. They often hold their pee at school, all day sometimes, hence encouraging to go potty as soon as they get home, and sometimes they don't realise that they need to go and have accidents occasionally, but not often now. They also often don't drink enough fluids, especially at school, even when encouraged profusely by people looking after them. They didn't seem to be in pain or struggle or anything at all when they went potty and were perfectly normal and happy and playing, chatting, eating etc before and after. I was just surprised at how strong their pee smelled and that it looked cloudy. Do you think this sounds like a UTI or is it just because they held their pee so long and maybe hadn't drank enough fluids?