If you're looking to expand your gear range and stick with Shimano, you may want to change the shifter and derailleur along with the cassette.
11spd SLX grade is about $30 for the shifter and $55 for the rear derailleur right now. I've had good luck with SunRace cassettes at 46T which are a little less than Shimano. But don't forget an 11 spd chain. Total upgrade will run about $150.
If assuming you currently have 10spd, you can get to 40T (sometimes 42T also) with an adapter (goatlink) to lengthen you current derailleur. It works okay and will get more gear range by not to 46T. I recently switched to Shimano 11spd on my Fatback and really like the extra range. I have a 1x with a 30T chainring so the range is even more important.
