Keep in mind macOS requires at least 20GB of free storage space on the boot drive so that macOS can operate properly. Plus SSDs perform & last longer if there is some empty space on them.
Also keep in mind when you upgrade to a new version of macOS it require even more free storage space. Due to the universal Big Sur installer to support both Intel & M1 Macs the requirement of free space can be as high as 35GB to 40GB for the upgrade and I would expect the same to be true for the next release of macOS next year as well.
I think you really need a 1TB SSD or you need to start storing items on external media since you are closing in on the limits of a 500GB SSD (depending on how much more you will be storing over the next five years or so). Just make sure you are backing up the external media as well as your boot drive. FYI, it is impossible to recover accidentally deleted data from an SSD plus an SSD can fail at any time without any warning signs.