#1. Quantity – Variant same line with Add to Cart under
To achieve layout like this

Use code like this to Code Injection > Footer
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
$('.ProductItem-quantity-add-to-cart .product-quantity-input').appendTo('.ProductItem-details .product-variants');
});
</script>
<style>
.ProductItem-details .product-variants {
display: flex;
}
</style>

result

#2. Move add to Cart above Description
You can edit Product Design > Choose this option

#3. Remove Add to Cart on Specific Product
Edit Product > Additional info > Add a Code Block > Paste this code
<style>
/* Remove add to cart */
div.sqs-add-to-cart-button-wrapper {
display: none !important;
}
</style>

#4. Remove Add to cart on All Pages
Use this CSS code
/* hide add to cart */
div.sqs-add-to-cart-button-wrapper {
display: none !important;
}

#5. Remove Add to Cart on Store Page
You can edit Store Page Section > Disable this option.

#6. Redirect Add to Cart to external link
You can edit each product > Additional Info > Add a Code Block > Paste this code. Replace Google with new url
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
$('.sqs-add-to-cart-button-wrapper').click(function() {
window.location.href = 'https://www.google.com';
});
});
</script>

#7. Add to cart to a custom image
Use this CSS code
div.sqs-add-to-cart-button {
background-image: url(https://cdn.pixabay.com/photo/2022/07/01/14/29/wheat-7295718__340.jpg) !important;
background-color: transparent !important;
background-size: cover;
background-repeat: no-repeat;
background-position: center center;
}

Result

Replace Pixabay with your image url
#8. Remove Add to cart from Quick View
Use this CSS code
div.lightbox-inner div.sqs-add-to-cart-button-wrapper {
display: none !important;
}
#9. Move Accordion Block under Add to Cart
Use this code to Website Tools > Code Injection > Footer
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
<script>
$(document).ready(function() {
$('section.ProductItem-additional .accordion-block').insertAfter('.ProductItem-details .sqs-add-to-cart-button-wrapper');
});
</script>
<style>
.ProductItem-details-checkout .accordion-block {
order: 5 !important;
}
</style>

Result

#10. Move Add to Cart under Price
Use this code to Code Injection > Footer
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
<script>
$(document).ready(function() {
$('.ProductItem-details-checkout .sqs-add-to-cart-button-wrapper').insertAfter('.product-price');
});
</script>

Result

#11. Hide Add to Cart on limited products
Use this code to Code Injection > Footer
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
<script>
$(document).ready(function() {
if ($('.product-scarcity').text().includes('Limited Availability')) {
$('.sqs-add-to-cart-button-wrapper').remove();
}
});
</script>

Result

#12. Move Add to Cart/Quantity under Product Description (Mobile)
@media screen and (max-width:767px) {
.ProductItem-quantity-add-to-cart {
order: 6 !important;
}
.ProductItem-details .ProductItem-product-price {
order: 7 !important;
}
}
#13. Change Add to Cart style to a text link
div.sqs-add-to-cart-button {
background-color: transparent !important;
border: none !important;
text-align: left !important;
padding-left: 0px !important;
}
div.sqs-add-to-cart-button * {
color: #000 !important;
text-decoration: underline;
}
#14. Add to Cart button background color
div.sqs-add-to-cart-button {
background-color: #f1f !important;
}
#15. Hide Add to Cart on Sold Out products
/* hide sold out add to cart */
.sold-out div.sqs-add-to-cart-button {
display: none !important;
}
#16. Move add to cart next to Quantity
#17. Move Description above Add to Cart (Mobile)
@media screen and (max-width:767px) {
.ProductItem-details .ProductItem-product-price {
order: 7 !important;
}
}