Yes. In this case, the measurement is stored in memory and will by synchronised with your account when the blood pressure monitor is connected to the internet again.
*credit to Sylvain of iHealth Labs EU
https://helpcenter.ihealthlabs.eu/hc/en-gb/articles/115005419785-iHealth-Clear-BPM1-Can-I-measure-my-blood-pressure-when-away-from-home-not-connected-to-my-Wi-Fi-network-