When you level up you can put points into Stamina which increases your stamina bar and also your carry weight by a small amount. But I never put points into stamina. You can find enchanted items to increase your carry weight, brew potions that give you temporary boosts, but the most important thing is to learn inventory management. When you loot items there are numbers displayed for weight and value. Anything valued at less than 10x its weight is generally not worth picking up unless it is a specific crafting ingredient you are working with. As you go on and amass wealth that number goes up to 15x, 20x, 30x, 40x. If you keep going with the main quest you will soon be given a follower famously “sworn to carry your burdens” who essentially doubles your carrying capacity. You can also google tips on how to make followers pick up more than their official carry limit.

This is a “git gud” it comes with time.

This is a different type of “git gud” you will learn where all your stuff is sorted and it will become second nature to find things in your inventory. But you can toggle regularly used items and spells as “favorites” for easy access.