Hi! How will the bars on the notch look like if i use one sim on a dual sim? Thank you!!

see https://support.apple.com/en-gb/HT207354

bars will be whole or split

Dual cell signals  On models with Dual SIM, the upper row of bars indicates the signal strength of the line you use for cellular data. The lower row of bars indicates the signal strength of your other line. If there’s no signal, “No Service” appears. To see the status icons with their corresponding cellular plan labels and carrier names, open Control Center.