My iPhone storage

My phone is an iPhone Xs.. the problem is that it keeps on telling me that my storage is full even when i downloaded Google photos app and started backing up my pictures and have already packed third of pictures on it which should give me more space now! But, it didnt give me a better storage on my phone even after deleting the pics from the deleted pictures file. So, it makes me feel that downloading Google photos and backing up the pics on it, have all gone in vain! So, is there anything for example that i need to do more than this or is there is something i need to clear from the phone after this to clean the storage? Because all apps wont even allow me to use them properly or to save anything freely because of the storage issue. Thanks in advance ❤️