Here's what I do as GM, to show a larger version of a token to the players: I select the token and touch 'z'. I right-click the enlarged image, and do "copy image URL". In chat, I type [img](xxx) where xxx is the pasted URL of the image, and that will show the image to the players. You might find that the text in the URL from the ? onwards needs to be deleted to make it work. You will probably find that if you use .webp images, you need to delete the ? onwards, and replace it with ?.png to fake the roll20 chat-handling code into just doing it. I wouldn't mind if this was a bit easier, but I don't do it often enough that its clunkiness makes me stop using it. (What I also do as GM is keep a separate campaign journal in a cloud document service, that the players have shared access to, and I have a prepared set of images to paste into the campaign journal as the adventure progresses. We keep a loot spreadsheet there as well, an xp spreadsheet, a document with rules clarifications, etc.)