Not if it is a simple plural. Simple plurals do not require an appostrophe.
sacrilegious salacious sameness scandalous scrupulous seamless separateness serous serendipitous sensuous serious shyness sinus sinuous slyness softness soreness sorceress soundness soundless...
For an English plural, the answer is never. Some words ending in the letter 's' are made plural by adding 'es', such as one bus, two buses or one class, two classes.
sea
present tense