A 5 year old child wetting the bed is very normal and nothing to worry about.
The bed wetting in your 5 year old is likely just caused by the bladder not growing fast enough and is not able to hold in the urine at night.
Bladder muscles in young children can also be weaker than they should be but overtime the child will outgrow the bed wetting as they grow.
I wet the bed myself when I was 5 and continued to wet the bed until age 15 which is when I finally quit wetting the bed.
I went to the doctor for it when I was a kid and my doctor told my mom that it was just that my bladder muscles weren't getting strong enough like they should but there was nothing to worry about and I would outgrow it once my bladder muscles matured when I got older and it did.
I wouldn't worry about the bed wetting until past age 17 and then it could be a problem.