Get some waterproof bed pads. I got all of mine from Amazon.
Nigh time dryness... is not something that is biologically attained, until even 7 years old. And is normal.
Kids, will have accidents. It is childhood.
And it fluctuates.
My son is 4, wears night time diapers to bed/naps. Fine.
My daughter, was already 5 years old and wearing night diapers. Then during that year, 'she' was ready for underwear.
Even at 7 years old, my daughter would occasionally have night time pee accidents. No biggie.
I had the waterproof bed pad directly under her. Clean up is easy. I don't have to change/wash the entire bedding. Only change the pad and put another one under her. And she goes back to sleep.
Pull-ups, at night, are useless. They don't hold much and the leak. And are expensive.
I never woke my kids at night just to pee. Nor did I withhold liquids.
They just naturally, get drier at night, her their biological maturity and development of their organs.
Each kid being different and per age.