Minecraft wiki entry for Vindicator, associated text: 5 and an additional 1–3 per naturally-spawned equipment.
0–1 emeralds when killed by the player. The maximum increases by 1 for every level of Looting, for a maximum of 0-4 with Looting III.
8.5% chance of dropping their normal or enchanted iron axe, which increases by 1% per level of Looting.
1 Ominous banner(in Java Edition), or illager banner in Bedrock Edition if they spawn as a raid captain.