If choosing a USB-C hub, you would be best advised to choose a hub with specifications that explicitly state compatibility with iPad.
Some USB-C hubs not all well suited for iPad. Some may only partially work, some may not work at all. Hubs that state suitability for iPad are more likely to offer trouble-free operation.
Whichever hub you choose, ensure that at least one port supports USB PD (Power Delivery) pass-through - as this port is used to provide power for both the hub and charging of the connected iPad. Hubs can incorporate a combination of additional USB-C ports, USB 2.0/3.1 Type-A ports, Ethernet LAN, HDMI, VGA, SD and microSD card-readers.
Perhaps consider Kingston, Anker, Hyperdrive and Satechi - although there are many others from which to choose. A Google Search for USB-C Hubs compatible with iPad will find a number of articles and recommendations.
Speaking of personal experience, the Kingston Nucleum has proven itself to be particularly flexible - featuring twin USB3.1 Type-A, downstream USB-C and SD/microSD card slots, HDMI, plus a power pass-through USB-C PD port that can accept +45W from a suitable USB power source.
If looking for an HDMI Adapter, be aware that very few USB-C HDMI adapters/hubs support HDCP - absence of which will inhibit the ability to output copy-protected HD media content from iPad to a connected monitor/TV over an HDMI connection.
The Apple USB-C Digital AV Multiport Adapter does support HDCP 2.0, but lacks some of the additional the flexibility afforded by some third-party USB-C hubs:
https://store.apple.com/uk/xc/product/MUF82ZM/A