My beloved MacBook Pro is getting old.

Hi!
My beloved MacBook Pro 2013 prime is at its end, but I refuse to upgrade due to the quality of my computer.
I use my laptop for day-to-day things. Over the last couple years, I have had to strategically download and delete software depending on what I want to use my laptop for.
I love playing Sims 4- if I have the Sims software on my laptop, I cannot have anything else downloaded.
I had to delete the game when I decided to go back to school and was using online education platforms.
When using detailed interactive websites such as Canva, my computer struggles to keep up and the fan will begin to run at full speed.
I'm guessing it's to do with processing power, memory and just it's age.
The battery is good enough that it doesn't worry me too much. The laptop battery does drain if I'm doing a lot on the laptop, but I'm typically at home anyway and it's on charge.
To give my laptop a new life, what products should I update? The processor, memory, battery?