A batteries screen on time and standby time will diminish over time from usage and charging and discharging the battery from charging it up.
Have a look in your phone's Battery and Device Care under battery to see whats using your battery @Sheshnag
A Samsung Experience Store or Samsung Service Centre can assess the phone and give a costing to replace the battery.
Or depending on the cost of replacing the battery and general condition of your phone you may want to consider selling / trading in that one and buy a newer model.
However you decide to proceed I wish you all the best.
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I have no affiliation with Samsung.