Haven’t played Rise specifically, but I have played others in the series and I would expect Rise hasn’t changed the progression system too much.

You don’t really have stats tied to a level or anything. You do have a hunter rank that increases with quest completion, but this is just to pace the challenge of the available monsters you can take on at any point. Once you prove yourself capable of handling monsters at a certain tier, harder hunts become available.

That being said, you do get stronger from crafting better armor and weapons, which most of the time have most of their crafting requirements come from a particular monster. So to craft the full Rathalos armor set, I would probably need to fight one several times. This will have higher base defense than an armor set from an easier monster, but armor pieces also give certain passive skills in a fight, so new armor is generally a sidegrade rather than a categorical upgrade. You can do a lot of experimentation if you care to make a unique build.

Anyway, I don’t feel like it’s grindy. Hunting monsters is literally the game, so you just progress by playing and getting better. You may need to repeat some quests if you have a specific goal but it would be self-imposed. You would never need to for story progression or anything.

The gameplay loop is kinda grindy at its core but it’s a very enjoyable kind of grind as long as you enjoy the combat mechanics and upgrade system. It ends up being as grindy as you want it to be.

You can play through the game and do the content the minimum required amount of times and probably get 40-50 hours out of the game but if you want high level gear to tackle the more challenging end game stuff then there’s basically no limit to how many hunts you can grind to collect materials.