Apple Mail App on MacBook - How to Reduce On-Computer Storage Requirements

In looking at the Mail App on my MacBook, it seems to be using almost 12GB of my 120GB SSD storage space, but only 260MB on my iPhone, and not much on my iPad either. And hardly anything on iCloud. (I use an IMAP protocol with the mail server from my ISP, Bell.)

I looked to see if there was a way to "optimize" mail storage on the MacBook, similar to the feature available with Photos, but did not find an option anywhere.

I only have ~14GB of free space on the MacBook SSD, and am running into trouble now with Photos syncing with iCloud -- with a note coming up on the Photos Library page on the MacBook indicating Syncing with iCloud Paused -- Not enough local storage space. I looked at removing any Apps that are taking up a lot of drive space, and had some luck, but the greatest potential benefit would appear to be getting the space that the Mail App requires on my computer reduced.

I do not have any issues with syncing Photos to iCloud with my iPhone or iPad and they have similar 120GB SSDs. But they have more free space -- and use much less space for the Mail App. (I do not have any issues with any other Apps syncing to iCloud on any of the devices, just Photos on the MacBook and that is the device that has the smallest free SSD space and the largest space that the Mail App uses.)

I wonder if anyone knows how to "optimize" storage requirements of the Apple Mail App on a MacBook -- How to make Mail just take up a little bit of space on a MacBook and rely more on the back-end ISP mail server for the rest (similar to how it seems to be able to be done on iPhone and iPad).

Any guidance and advice would be appreciated.

Thanks,