Unfortunately, setup mode does not offer such features, so we recommend testing meshes and weights in animate mode.
Perhaps you are used to a workflow in the older versions, and I would like to add these just in case: Even in animate mode, bones can be bound to meshes since Spine 3.8.77, and meshes can be edited since Spine 4.0.
Also, the Favor tool, added in 4.0, allows you to return bone transforms to their setup mode values at any time during the animation by using Setup mode:
Graph - Spine User Guide: Favor
Thanks to these updates, the setup process is now very efficient with good use of the animate mode.
There is a blog post that provides a concise summary of our recommended rigging workflow, which may be helpful:
Blog: Rigging new poses - Spine workflow tutorial