Versatile lens for event photography?

hi everyone! I have a canon eos rebel t6 that i bought in Nov 2020 and came with a 18-55mm and 75-300mm. I recently started taking pictures for my nonprofit job and I’m looking for an affordable lens (ideally no more than $700 used) that i can add to my kit for pictures of participants at events both indoors (conferences/retreats) and outdoors (demonstrations/marches) that can capture candids but also group pictures (our largest crowd outside was recently 400). This is a lens I would also want to use recreationally to get pictures of my family, pets and youth sporting events.

I feel like that’s a lot to ask for but if anyone has any recs that would be great. I haven’t used my camera for a while so despite having it for nearly 5 years I’m still very much a beginner and none of my research has yielded a lot of answers. appreciate any input!