1. 네비게이션 타이틀 폰트 사이즈 변경

let attrs = [
            NSAttributedString.Key.foregroundColor: UIColor.black,
            NSAttributedString.Key.font: UIFont(name: "Georgia-Bold", size: 26)!
        ]

        UINavigationBar.appearance().titleTextAttributes = attrs

2. 네비게이션 barbutton 사이즈 변경

lazy var createButton : UIBarButtonItem  = {
        let button = UIButton()
        button.setImage(UIImage(systemName: "plus")?.imageResized(to: CGSizeMake(26, 26)), for: .normal)
        button.addTarget(self, action: #selector(createButtonTapped), for: .touchUpInside)
        return UIBarButtonItem(customView: button)
    }()

3. 이미지 사이즈 변경 extension

import UIKit
extension UIImage {
    func imageResized(to size: CGSize) -> UIImage {
        return UIGraphicsImageRenderer(size: size).image { _ in
            draw(in: CGRect(origin: .zero, size: size))
        }
    }
}