Yes it's normal for a 4 year old child to have potty accidents and it's something to be expected.
Kids at 4 and even 5 and 6 years old can have potty accidents and may wet their pants or poop their pants in the day due to being too busy playing and not get up to go to the bathroom.
If your 4 year old has potty accidents do not scold them or punish them but just let them know that they need to try again to go to the bathroom when they feel the urge.
Sometimes you need to set a timer and take your 4 year old child to the potty at set schedules to allow them to relieve themselves.
Sometimes it takes awhile before the 4 year old goes to the bathroom on their own and doesn't have potty accidents.
At night is a different thing as that can be caused by bed wetting which is not the child's doing as they cannot help wetting the bed.
If the child is not dry at night either have them wear a pull up or a regular diaper to keep them dry and their bed dry if they will wear it.