QMultiLinePushButton.h:

#ifndef QMULTILINEPUSHBUTTON_H
#define QMULTILINEPUSHBUTTON_H

#include <QPushButton>
class QLabel;

class QMultiLinePushButton : public QPushButton
{
    Q_OBJECT
public:
    QMultiLinePushButton(QWidget *parent = nullptr);

    void setText(const QString &text);
    QString text() const;

    void setTextAlignment(Qt::Alignment align = Qt::AlignCenter);

protected:
    virtual void resizeEvent(QResizeEvent *event); // qpushbutton protected methods

private:
    QLabel* m_label;

};

#endif // QMULTILINEPUSHBUTTON_H

QMultiLinePushButton.cpp

#include "QMultiLinePushButton.h"
#include <QLabel>
#include <QHBoxLayout>
#include <QResizeEvent>
#include <QDebug>

QMultiLinePushButton::QMultiLinePushButton(QWidget *parent)
{
    this->setParent(parent);
    m_label = new QLabel(this);
    m_label->setWordWrap(true);
    m_label->setAlignment(Qt::AlignCenter);

//    QHBoxLayout* layout = new QHBoxLayout(this);
//    layout->addWidget(m_label, 0, Qt::AlignCenter);

//    layout->setMargin(1);
    qDebug() << geometry();
}

void QMultiLinePushButton::setText(const QString &text)
{
    m_label->setText(text);
}

QString QMultiLinePushButton::text() const
{
    return m_label->text();
}

void QMultiLinePushButton::setTextAlignment(Qt::Alignment align)
{
    m_label->setAlignment(align);
}

void QMultiLinePushButton::resizeEvent(QResizeEvent *event)
{
    qDebug() << geometry();
    m_label->setFixedSize(size());
    m_label->setStyleSheet("text-align: left;");
    m_label->setFont(this->font()); // why is the font black?
    event->accept();
}

Here is the form:

Each text has the text which is "Deneme bir iki üç dört beş altı yedi sekiz dokuz on". Meaning: "Trying one two ... nine ten" in English

Best regards. Have a nice day.