How to make a poster on phone

[Unusualllly]

If I want to make a e-poster to advertise an event or a party invitation to send on whatsapp....which app should I use? I have no idea what to use/how to do this on my phone (no computer).
Thank you!!

Download the Canva app.
lots of templates

Canva is fab!

Definitely Canva. I use it professionally for quick social stuff and personally. The app is free though some templates have a charge. You can also upgrade for more options/templates/styles etc

Brilliant, thank you