Samsung routines can do exactly this. You can customize it to only charge up to 85% (though no way to set 80% or 90% or something) and then have it not charge u

Samsung routines can do exactly this. You can customize it to only charge up to 85% (though no way to set 80% or 90% or something) and then have it not charge until two hours before your alarm, either fast charge or slow charge.