It's pretty easy. You either get it from Cargo (the Rust package manager) or add a custom repo to apt.

Cargo is the easier and safer option: curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh && cargo install eza

Custom apt repo:

sudo apt update
sudo apt install -y gpg

sudo mkdir -p /etc/apt/keyrings
wget -qO- https://raw.githubusercontent.com/eza-community/eza/main/deb.asc | sudo gpg --dearmor -o /etc/apt/keyrings/gierens.gpg
echo "deb [signed-by=/etc/apt/keyrings/gierens.gpg] http://deb.gierens.de stable main" | sudo tee /etc/apt/sources.list.d/gierens.list
sudo chmod 644 /etc/apt/keyrings/gierens.gpg /etc/apt/sources.list.d/gierens.list
sudo apt update
sudo apt install -y eza

In my opinion though, you should also try lsd. It's even better than eza. You can also get it from Cargo, just a simple cargo install lsd.