In the Data Studio Insights, the computation "Company Size" uses 4 labels to classify companies by company size (derived from Clearbit's employees data).
vSMB: 1 to 10 employees
SMB: 11 to 100 employees
MidMarket: 101 to 1000 employees
Ent: 1001 or more employees
If you would like to create your own classification of company sizes that contains different thresholds and see how each segment of companies performs, you can create a new Computation following these instructions and then look at the Customer Fit Insights for this computation.