Tried making my own tokens but having some problems with shrinking them to fit the grid

I thought it would be nice to try drawing my own tokens for the player characters in the game I'm going to DM next week but having more or less finished one I tried uploading it and I can't seem to increase the quality of the image when shrunk down to fit the map's grid. I've tried all kinds of image sizes and resolutions but no luck so far. Any ideas what I can do because as it stands it just doesn't look so great next to other assets. Here's the token at regular size next to the size it needs to be.

What image format are you using? Have you looked at the guidelines here and here ?

I've been using PNG for the most part. I did look at the guidelines but it seems like no matter the image size the token still looks the same when scaled down to fit the grid.

Very distinct linework like that may not scale cleanly. Are you starting from a vector source? If so, try to ensure that your line weights are a multiple of your ultimate reduction size. Even that will only help you at certain zoom settings.

When we make token assets for sale the guidelines say to aim for 280x280 and 72 pixels/inch. Each grid square is 70 pixels so we are making 4x4 tokens that scale down to 1x1. Hope that helps!