Mod 1.19.2, 1.18.2) allows for smaller nether portals. It is a minimalistic mod which allows you to create smaller nether portals.
Note: Teleporting from a smaller portal to teleport is currently not possible in Minecraft. This causes the player to be placed underneath the portal on its other side. This mod will detect the problem and teleport the player to the portal in its place. It will detect the blocks below and replace them with obsidian if they are Netherrack, Soul Sand, or Air blocks to avoid unwanted deaths. If necessary, it will also create an Air Gap.