I've made numerous beers with 40-50% rye malt. It is very mild in flavor, bready, slightly earthy, and not spicy. Any spiciness probably comes from the hops, or perhaps the yeast. What it does: super creamy head with outstanding retention, and a very heavy body. In smaller amounts, you'll get the benefits on head and creaminess but without the very heavy body.
Note: It can also add a grayish hue and permanent haze to the beer in higher amounts. Not like NEIPA, but a very strange soft muddy "sheen". Still clear, but not as clear as you can get with zero rye.
I think 15-20% is a good place to start to see if you like the benefits, while limiting what it could do that might not be as desirable if you used more than that.