We have SharePoint SPFx web part (developed using jQuery).
We want to show these web parts responsive in the all devices.
Do we need to use bootstrap or any media query?
SharePoint Stack Exchange is a question and answer site for SharePoint enthusiasts. It only takes a minute to sign up.Sign up to join this community
As per my understanding, SPFx webparts are responsive by design. So, most of the times you don't need to use bootstrap or media query.
It is recommended to use Office UI Fabric React components (not compulsory) which is a responsive and simple for you to create web experiences by using the Office Design Language. Read more at Design considerations for SharePoint client-side web parts.
But if you are familiar with Bootstrap then you can use it in your webpart if you want. below documentation will help you on working with CSS in SPFx:
Additional References: This will help you on using bootstrap in SPFx and responsive design.