How do I use the API to deploy an Image and Resize at the same time?

While there is no way to tell the CLI to wait until your Linode has finished being created, it is able to report that data back to a script, which then waits to run the resize command until the Linode is ready. The following is an example script:

#!/usr/bin/env bash

## Create a Linode, but don't boot it yet...
LABEL=<Linode Label>
LINODE_ID="$(linode-cli linodes create --text \
                          --label "$LABEL" \
              --root_pass <root pass> \
              --region "us-east" \
              --type "g6-nanode-1" \
              --image <image name> \
              --booted false | grep "\b$LABEL\b" | awk '{print $1}'
)"

## Check to see if the new Linode is finished being created...
while [[ "$(linode-cli linodes list --text | grep "\b${LABEL}\b" | grep '\bprovisioning')" ]]; do
    sleep 1
done

sleep 3m
## Get the Disk to be resized's ID
DISK_ID="$(linode-cli linodes disks-list --text $LINODE_ID | awk '/VPS-IMAGE-01/{print $1}')"
echo "$LABEL"
echo "$LINODE_ID"
echo "$DISK_ID"

## Resize the Linode
linode-cli linodes disk-resize "$LINODE_ID" "$DISK_ID" --size "20200"

Use terraform, it should support what you want, you can define sizes of disks etc when it creates instance.