Immersive Portals Mod 1.15.2/1.15.1/1.14.4 IP allows you to see another dimension through the portals and enter them without any loading screen. The mod also supports horizontal portals to hell and land.
In addition to giving the possibility to see through the portals, when you pass through them, you will not have any loading time. In addition, the mod supports shaders and will therefore be compatible with Optifine for version 1.14.4 of Minecraft.