So I recently upgraded from a d3500 with the two kit lenses it come with to a Sony a7 iii it came with the 28-70 mm kit lens but but I don’t feel like it’s very sharp and the bokeh is not what I am looking for

Photography style: mixture of street photography day and night, I like to take pictures of cars like at car shows portraits every now and then

I would ideally like a fixed lens something that is easy to carry around and just shoot on the go and I’m willing to spend any where from 400-600 dollars but if it’s a really good lens I could fork up a bit more

Thank you guys for your help looking forward to being part of the community