Optiscale

Requires Forge

Client-side mod 

New to version 1.03

Add new config option 'Override List': 
Allows you to override specific screens with custom scaling.

E.g., Make chest screens bigger:
net.minecraft.client.gui.screens.inventory.ContainerScreen=500
Above sets Chest screen to use 500% scaling
To help with setting the above, there is a new DEBUG level log that the mod prints whenever you open a new screen with the screen name: 
[Optiscale] Detected new screen=net.minecraft.client.gui.screens.inventory.InventoryScreen
Use this to set a custom scale or set this to 0 to blacklist Optiscale from scaling this screen
You can also give the name of the package instead of the screen, e.g., net.minecraft.client.gui.screens.inventory.*=200 to rescale all screens that are in that specific package

1.04:
Add the ability to override screens based on their "menu name" or the title of the screen.
e.g., To enlarge the 'Modern Life' mod Printer screen, you can write Printer=600

Note: Mod is totally resigned for 1.20.1.

Instead of integrating with the video screen, the scaling is now only configurable with a hotkey (default: F7, change in Key Bindings menu).

This is so that it can work even with custom video screen UIs such as Iris/Oculus.

This mod will change your Video Settings "GUI Scale" option into a slider that allows for a wider range of configurations. 

Other mods exist with this functionality but this mod is compatible with both vanilla and optifine. This mod also allows a much more fine-grained tuning than others which only give integer values like 0, 1, 2, 3, whereas this offers any value you want like 1.7x for example.

In vanilla the scaling options are [1, 2, 3] but with this mod you can choose between 150% to 450% using a slider.

The vanilla scaling options correspond to the following percentages:

1: 200%

2: 300%

3: 400%