Yes, this is usually possible. A white label portal can be set up with sub agent accounts, so the smaller agents you work with log in and search and book for themselves instead of sending you every request by phone or message. Each agent gets their own login, sees only their own bookings, and books on a site that carries your branding, so your business stays the one they deal with.
In most setups you keep control of the commercial side. You can decide the markup that each agent or group of agents sees, approve new agent registrations before they can start booking, switch an account off if you stop working with that agent, and pull booking reports for the whole network or for one agent at a time. Many agencies also run their sub agents on a prepaid wallet or a credit limit that you set, so bookings only go through when the agent has funds or room on their limit with you.
How much of this you get does depend on your plan and on how your portal is configured, and the payment side depends on which payment methods and gateway you have connected. Some suppliers also set rules about who their content can be resold to, so it is worth checking that before you promise a large agent network full access to everything on your site.
The next thing to do is write down roughly how many agents you want to onboard, whether you want them paying upfront or on credit with you, and whether they should all see the same markup, then share that with our team so your portal can be configured to match.