This is an offshoot of MC-243216, with the issue being that you are unable to change the render distance on Realms (I'm using Java, but presumably you can't change it on bedrock either). Essentially in 1.18, from what I understand, an option was added to separate render distance from the players and the servers (incl. realms), making it so the render distance for players is limited to whatever it is set to for the server the player joins. In theory this would be fine, however no option was ever added to the realms files to permit the changing of render distance. Thus in realms worlds, render distance is capped off at 8-10, with no options or ways to change it. On servers you can change the render distance using the server properties file, but no such option exists for realms. 

This is still an issue in 1.18.1