Yes you can buy a casket before you die and pre plan your funeral and pay the funeral home for your funeral expenses before you actually die.
That way you get the casket you want and you have your wishes for your funeral carried out as you plan it yourself.
Your family then doesn't have to deal with the funeral and funeral expense and it will be the best thing you can do.
My Grandma bought her casket and paid for her funeral through monthly payments to the funeral home about 10 years before she died.
The funeral home constantly had the same caskets coming in so while they didn't store her casket for her and she didn't bring the casket home she did have the casket she wanted at her funeral.