Hello Po
Yes, that is correct. The VLAN itself can be considered a virtual layer 2 switch. The SVI interface, which is the same thing as the VLAN interface, is a virtual interface that exists within the VLAN and is assigned an IP address. It functions as the default gateway of the specific VLAN/subnet.
When a host on the VLAN wants to send data to some device on another network, say to a web server on the Internet, it will send an IP packet with a destination IP of the webserver in the IP header. However, it knows that the destination IP is outside of its own subnet, so it puts the MAC address of the SVI (which is the default gateway) in the destination address field of the frame. More detail on this process is found in this post:
Keep in mind that this process is the same whether you use an SVI as the default gateway or an actual physical router.
I hope this has been helpful!
Laz