Hello @adibhb,
You can use HTML in the Form tab content.
Knowing this, you could use a some HTML markup this way:
<div class="buttons-container">
[submit "Send Message"]
<a href="tel:155555555" class="btn call">Call</a>
<a href="https://wa.me/155555555" class="btn whatsapp">WhatsApp</a>
</div>
Then, you’ll need to apply some CSS rules to that markup:
.buttons-container {
display: grid;
width: 100%;
grid-template-columns: 1fr 1fr;
grid-template-rows: auto;
grid-template-areas: "submit call"
"whatsapp whatsapp"
"ajax-loader ajax-loader";
column-gap: 1em;
}
.buttons-container a,
input[type="submit"] {
border: 1px solid #28a745;
background: none;
border-radius: 5px;
color: #28a745;
display: block;
font-weight: bold;
margin-top: 10px;
padding: 10px;
text-align: center;
text-decoration: none;
width: 100%;
}
.buttons-container a:hover,
.buttons-container .wpcf7-submit:hover {
background: #28a745;
color: #fff;
text-decoration: none;
}
.buttons-container .wpcf7-submit {
grid-area: submit;
}
.buttons-container a.call {
grid-area: call;
}
.buttons-container a.whatsapp {
grid-area: whatsapp;
}
.buttons-container .ajax-loader{
grid-area: ajax-loader;
}
Finally, you’ll get something similar to this:

Please note some themes may use extra CSS that overrides this CSS rules, and you still need to add the WhatsApp icon ??
Hope it helps you!
Best regards,
Yordan.